At least in tags like sas, most questions asked by new users are frequently tagged with random tags that aren't appropriate for the topic. Most commonly, they are tags that are very specific to the user's question, like this question which adds invert, which is not really a useful tag.
I'd like to see a minimum reputation (say 50 or 100) for tagging a question with tags like this. I'm not totally sure what the right solution is there - tags with at least 100/200/500 questions? Tags with >0/>10/>100 followers? Unfortunately some of this is a 'I know it when I see it' type of thing, but I'm sure a reasonable rule could be created. Limiting to just
tags with zero uses doesn't work, because lots of times other people have used these same tags inappropriately.
I also have a feeling this may be related to the 'suggested tags' at the bottom; how are those generated? If they're just a word match, then we might want to have some (more) limits on what tags show up in those tags - particularly if it could be done on a 'major'-tag basis (ie, sas has a relatively limited set of things that would make sense associated with it).
This is probably somewhat a rehash of this thread, but I don't see any result of that thread, so I'd be curious if we could reopen this for discussion.