One problem with filtered results is indicating that filtering is active and that hence some results are not shown.
- Is filtering the same as searching? the answers suggest that there are differences, but that the two lie on a spectrum.
A recurring problem with filtering is that the filtering interface can get extremely complex with large numbers of options to include and exclude. Here's an alternative approach for that kind of filtering problem.
Related Tags search
Creating a 'Filtering' Question
The most important point when creating a filtering question is to review previous filtering questions. In your question be clear about what aspect they don't address.