Certain tags, when searched for, give 1 page of results but no more, even though there are more results. This seems to be because they are replaced by an alias... but only some aliased tags do this. I suspect this happens for aliases that have a negative count in the alias listings. Flat_chest and anal_creampie, for instance.
Searching for what the aliased-into tag is works. Small_breasts returns all the results that flat_chest should've given.
Updated by ikdind