diff -u b/core/modules/migrate/src/Audit/AuditorInterface.php b/core/modules/migrate/src/Audit/AuditorInterface.php
--- b/core/modules/migrate/src/Audit/AuditorInterface.php
+++ b/core/modules/migrate/src/Audit/AuditorInterface.php
@@ -23,10 +23,8 @@
    * @throws \Drupal\migrate\Audit\AuditException
    *   If the audit fails.
    *
-   * @return array
-   *   If the audit detects no potential conflicts, an empty array is returned.
-   *   Otherwise, the return value will be an array with a single element: a
-   *   string explaining the nature of the conflict, keyed by the migration ID.
+   * @return \Drupal\migrate\Audit\AuditResult
+   *   The result of the audit.
    */
   public function audit(MigrationInterface $migration);
 
@@ -36,9 +34,8 @@
    * @param \Drupal\migrate\Plugin\MigrationInterface[] $migrations
    *   The migrations to audit.
    *
-   * @return array
-   *   An array of potential conflict information, keyed by migration ID. See
-   *   audit() for more information.
+   * @return \Drupal\migrate\Audit\AuditResult[]
+   *   The audit results, keyed by migration ID.
    */
   public function auditMultiple(array $migrations);
 
diff -u b/core/modules/migrate/src/Audit/IdAuditor.php b/core/modules/migrate/src/Audit/IdAuditor.php
--- b/core/modules/migrate/src/Audit/IdAuditor.php
+++ b/core/modules/migrate/src/Audit/IdAuditor.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\migrate\Audit;
 
+use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Drupal\migrate\Plugin\MigrationInterface;
 
 /**
@@ -9,6 +10,8 @@
  */
 class IdAuditor implements AuditorInterface {
 
+  use StringTranslationTrait;
+
   /**
    * {@inheritdoc}
    */
@@ -32,9 +35,11 @@
     }
 
     if ($destination->getHighestId() > $id_map->getHighestId()) {
-      return static::conflict($migration);
+      return AuditResult::fail($migration, [
+        $this->t('The destination system contains data which was not created by a migration.'),
+      ]);
     }
-    return [];
+    return AuditResult::pass($migration);
   }
 
   /**
@@ -46,29 +51,9 @@
     foreach ($migrations as $migration) {
-      $conflicts += $this->audit($migration);
+      $migration_id = $migration->getPluginId();
+      $conflicts[$migration_id] = $this->audit($migration);
     }
     ksort($conflicts);
     return $conflicts;
   }
 
-  /**
-   * Builds a conflict array.
-   *
-   * @param \Drupal\migrate\Plugin\MigrationInterface $migration
-   *   The migration that has the conflict.
-   *
-   * @return array
-   *   The conflict. See \Drupal\migrate\Audit\AuditorInterface::audit() for
-   *   information on the format of the return value.
-   */
-  public static function conflict(MigrationInterface $migration) {
-    $base_id = $migration->getBaseId();
-
-    $conflict = [
-      $base_id => $base_id,
-    ];
-    $conflict[$base_id] = (string) $migration->label();
-
-    return $conflict;
-  }
-
 }
reverted:
--- b/core/modules/migrate_drupal/migrate_drupal.services.yml
+++ a/core/modules/migrate_drupal/migrate_drupal.services.yml
@@ -16,5 +16,3 @@
       - '@module_handler'
       - '\Drupal\migrate_drupal\Annotation\MigrateCckField'
     deprecated: The "%service_id%" service is deprecated. You should use the 'plugin.manager.migrate.field' service instead. See https://www.drupal.org/node/2751897
-  migrate.audit:
-    class: Drupal\migrate\Audit\IdAuditor
diff -u b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
--- b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
+++ b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
@@ -9,7 +9,7 @@
 use Drupal\Core\Render\RendererInterface;
 use Drupal\Core\State\StateInterface;
 use Drupal\Core\Url;
-use Drupal\migrate\Audit\AuditorInterface;
+use Drupal\migrate\Audit\IdAuditor;
 use Drupal\migrate\Plugin\migrate\destination\EntityContentBase;
 use Drupal\migrate\Plugin\MigrationPluginManagerInterface;
 use Drupal\migrate_drupal\Plugin\MigrateFieldPluginManagerInterface;
@@ -90,17 +90,14 @@
    *   The field plugin manager.
    * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
    *   The module handler.
-   * @param \Drupal\migrate\Audit\AuditorInterface $auditor
-   *   The auditor service.
    */
-  public function __construct(StateInterface $state, DateFormatterInterface $date_formatter, RendererInterface $renderer, MigrationPluginManagerInterface $plugin_manager, MigrateFieldPluginManagerInterface $field_plugin_manager, ModuleHandlerInterface $module_handler, AuditorInterface $auditor) {
+  public function __construct(StateInterface $state, DateFormatterInterface $date_formatter, RendererInterface $renderer, MigrationPluginManagerInterface $plugin_manager, MigrateFieldPluginManagerInterface $field_plugin_manager, ModuleHandlerInterface $module_handler) {
     $this->state = $state;
     $this->dateFormatter = $date_formatter;
     $this->renderer = $renderer;
     $this->pluginManager = $plugin_manager;
     $this->fieldPluginManager = $field_plugin_manager;
     $this->moduleHandler = $module_handler;
-    $this->auditor = $auditor;
   }
 
   /**
@@ -113,8 +110,7 @@
       $container->get('renderer'),
       $container->get('plugin.manager.migration'),
       $container->get('plugin.manager.migrate.field'),
-      $container->get('module_handler'),
-      $container->get('migrate.audit')
+      $container->get('module_handler')
     );
   }
 
@@ -494,15 +490,24 @@
     $migrations = $this->pluginManager->createInstances($migration_ids);
 
     $translated_content_conflicts = $content_conflicts = [];
-    foreach ($migrations as $migration) {
-      $audit = $this->auditor->audit($migration);
-      $destination_plugin = $migration->getDestinationPlugin();
 
-      if ($destination_plugin instanceof EntityContentBase && $destination_plugin->isTranslationDestination()) {
-        $translated_content_conflicts += $audit;
+    $results = (new IdAuditor())->auditMultiple($migrations);
+
+    /** @var \Drupal\migrate\Audit\AuditResult $result */
+    foreach ($results as $migration_id => $result) {
+      // If the migration passed the audit, we don't need to do anything.
+      if ($result->passed()) {
+        continue;
+      }
+
+      $destination = $result->getMigration()->getDestinationPlugin();
+      $definition = $destination->getPluginDefinition();
+
+      if ($destination instanceof EntityContentBase && $destination->isTranslationDestination()) {
+        $translated_content_conflicts[$migration_id] = $definition['label'];
       }
       else {
-        $content_conflicts += $audit;
+        $content_conflicts[$migration_id] = $definition['label'];
       }
     }
     if (empty($content_conflicts) && empty($translated_content_conflicts)) {
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/migrate/src/Audit/AuditResult.php
@@ -0,0 +1,146 @@
+<?php
+
+namespace Drupal\migrate\Audit;
+
+use Drupal\Component\Render\MarkupInterface;
+use Drupal\migrate\Plugin\MigrationInterface;
+
+/**
+ * Encapsulates the result of a migration audit.
+ */
+class AuditResult implements MarkupInterface, \Countable {
+
+  /**
+   * The audited migration.
+   *
+   * @var \Drupal\migrate\Plugin\MigrationInterface
+   */
+  protected $migration;
+
+  /**
+   * The result of the audit (TRUE if passed, FALSE otherwise).
+   *
+   * @var bool
+   */
+  protected $status;
+
+  /**
+   * The reasons why the migration passed or failed the audit.
+   *
+   * @var string[]
+   */
+  protected $reasons = [];
+
+  /**
+   * AuditResult constructor.
+   *
+   * @param \Drupal\migrate\Plugin\MigrationInterface $migration
+   *   The audited migration.
+   * @param bool $status
+   *   The result of the audit (TRUE if passed, FALSE otherwise).
+   * @param string[] $reasons
+   *   (optional) The reasons why the migration passed or failed the audit.
+   */
+  public function __construct(MigrationInterface $migration, $status, array $reasons = []) {
+    if (!is_bool($status)) {
+      throw new \InvalidArgumentException('Audit results must have a boolean status.');
+    }
+    $this->migration = $migration;
+    $this->status = $status;
+    array_walk($reasons, [$this, 'addReason']);
+  }
+
+  /**
+   * Returns the audited migration.
+   *
+   * @return \Drupal\migrate\Plugin\MigrationInterface
+   *   The audited migration.
+   */
+  public function getMigration() {
+    return $this->migration;
+  }
+
+  /**
+   * Returns the boolean result of the audit.
+   *
+   * @return bool
+   *   The result of the audit. TRUE if the migration passed the audit, FALSE
+   *   otherwise.
+   */
+  public function passed() {
+    return $this->status;
+  }
+
+  /**
+   * Adds a reason why the migration passed or failed the audit.
+   *
+   * @param string|object $reason
+   *   The reason to add. Can be a string or a string-castable object.
+   *
+   * @return $this
+   */
+  public function addReason($reason) {
+    array_push($this->reasons, (string) $reason);
+    return $this;
+  }
+
+  /**
+   * Creates a passing audit result for a migration.
+   *
+   * @param \Drupal\migrate\Plugin\MigrationInterface $migration
+   *   The audited migration.
+   * @param string[] $reasons
+   *   (optional) The reasons why the migration passed the audit.
+   *
+   * @return static
+   */
+  public static function pass(MigrationInterface $migration, array $reasons = []) {
+    return new static($migration, TRUE, $reasons);
+  }
+
+  /**
+   * Creates a failing audit result for a migration.
+   *
+   * @param \Drupal\migrate\Plugin\MigrationInterface $migration
+   *   The audited migration.
+   * @param array $reasons
+   *   (optional) The reasons why the migration failed the audit.
+   *
+   * @return static
+   */
+  public static function fail(MigrationInterface $migration, array $reasons = []) {
+    return new static($migration, FALSE, $reasons);
+  }
+
+  /**
+   * Implements \Countable::count() for Twig template compatibility.
+   *
+   * @return int
+   *
+   * @see \Drupal\Component\Render\MarkupInterface
+   */
+  public function count() {
+    return count($this->reasons);
+  }
+
+  /**
+   * Returns the reasons the migration passed or failed, as a string.
+   *
+   * @return string
+   *
+   * @see \Drupal\Component\Render\MarkupInterface
+   */
+  public function __toString() {
+    return implode("\n", $this->reasons);
+  }
+
+  /**
+   * Returns the reasons the migration passed or failed, for JSON serialization.
+   *
+   * @return string[]
+   */
+  public function jsonSerialize() {
+    return $this->reasons;
+  }
+
+}
only in patch2:
unchanged:
--- a/core/modules/migrate/src/Plugin/migrate/destination/Entity.php
+++ b/core/modules/migrate/src/Plugin/migrate/destination/Entity.php
@@ -94,6 +94,10 @@
    *   The list of bundles this entity type has.
    */
   public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, EntityStorageInterface $storage, array $bundles) {
+    $plugin_definition += [
+      'label' => $storage->getEntityType()->getPluralLabel(),
+    ];
+
     parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
     $this->storage = $storage;
     $this->bundles = $bundles;