I feel that the concern of improper tagging is alleviated by a) the editable community tag (although 2 of those might be cool)
The editable community tag is a good feature but it is still limited to the list of tags that are currently out there now. You could create a new tag just for one post but the chances are that you will prevent people from ever seeing it rather than creating a new and useful category.and b) the follow/share structure, as long as you have confidence in who you follow.
Right and thats probably the most important factor in the limitations of tags right now, because they have less power to filter for things you find interesting (we have generic buckets like #thehumancondition rather than targetted tags) you need to rely on the people you follow which causes its own problems (Users with the most followers decide the content for everyone else). I know hubski is intended to be a person follow based site but tags (could/should?) provide a balancing force against that power struggle. I often feel "stuck" on tags. Sometimes I can't come up with one and sometimes I come up with four. While it's not ideal, and for instance "tag suggestions" that pop up might be nice, I don't think it's "broken."
Yep, I feel stuck so I lump it into "something" in most cases. Tag suggestions are needed I think. "broken" is debatable, I don't think they are as powerful or as useful as they should be.