There has been a lot of misuse of various tags lately (look at how many I've stripped of andromorph in recent history) since the site revamped its options. I'm willing to bet these are mostly concentrated in the tags you click on rather than type in while uploading an image. Not everybody knows there's an actively maintained tagging wiki.

My suggestion is to add a ? Button that provides a basic tooltip when it's hovered over in order to better assist people unfamiliar with tags.