Be cautious with creating new tags
From FAQ about tags: Try to avoid creating new tags. Instead, check if there is some synonym that already has a popular tag. It's not easy to keep balance between too specific tags and not having enough tags, but tags for specific theorems are usuallyit is always good to search first and to ask yourself, whether newly created tag is not too specific, perhaps with the exception of some very important ones. (Of course, you can disagree with the removal of the tag you've created, and there is possibility for further discussion, if needed.)
From [FAQ about tags](http://meta.math.stackexchange.com/questions/107/faq-for-math-stackexchange/128#128): *Try to avoid creating new tags. Instead, check if there is some synonym that already has a popular tag.* It's not easy to keep balance between too specific tags and not having enough tags, but tagsit foris specificalways theoremsgood areto usuallysearch toofirst specific,and perhapsto withask theyourself, exceptionwhether ofnewly somecreated verytag importantis onesnot too specific. (Of course, you can disagree with the removal of the tag you've created, and there is possibility for further discussion, if needed.)
The first part of the comment seems to be sufficient in cases when retagging or removal of tags is clear-cut.