Most of the time if it has a 'character', 'pairing' or 'person' tag that's all that's really required. If you ask for it in your post you should tag for it. But then again if you have a het pairing tag i.e Sam/Jess (or a slash one if it's slash) there's really no need to use the 'het' tag if you don't want to. It's kind of redundant. A lot of tags are, but getting rid of them isn't an option cause a lot of the older posts (before the pairing tag rule was implemented) don't have pairings on them just the tag het or slash or others. If I think a tag doesn't belong, I'll remove it same goes for adding a tag. Hope that ramble made sense. =)