I love the insinuations in this answer/question in the FAQ:
For Developers
Q. What if I don't agree with a tag that has become popular for my game?
A. Tags can be a good indicator of when there is a mismatch between how you perceive your game, and how your game is perceived by customers. Often this is simply because there is some piece of information regarding the game that customers feel is missing from the store page.
"Pay to Win" and "Grind to Win" tags splattered over deserving F2P games with no way for the developer to remove it by the sound of it.
How long until every game on steam is tagged penis?
They'd probably lump that in with the "no swear words" exception, would be interesting to see what tags you could get away with though, and how many games you could get them plastered on before valve take action.
EDIT: lol, TF2 already has a "Hats" tag
EDIT2: WE MUST MAKE IT HAPPEN:
http://i3.photobucket.com/albums/y79/Hulinut/hatsimulator.png