I generally have trouble getting tag combinations to work, not only it increases the tag count required for the desired search but for an inherent psychological reason and inevitable limitation in the tagger's knowledge gentags are much more likely to be missed than the potential character tag. It's not hard to picture why: remembering specific attire of your favorite character is more taxing than merely remembering the name of the skin. The case for character tags is clearer when you factor all the subtle components that would define a specific skin and how losing a few of them even either by the artist's decision or the scene depicted (say: having sex) wouldn't make them a different character or skin. I concede there are simpler skin designs than others that could in fact be achieved by 2-tag search yet having character skins is all around easier for everyone.