I have faceted search working using Search API (with Search Views), Facet API, and Views. Love love love these modules.
I have 5 facets set up to narrow by Color, Size, Pattern, Shape, and Condition.
When I select RED under Color, I get all < red > results. GREAT.
If I then select LARGE under Size, I get all < red AND large > results. GREAT.
But when I select a second Color, say BLUE, suddenly I get only results that were tagged as < red AND blue AND large >.