How do I deal with problemic tags?

I have tried to get rid of the off-the-wall tags some clowns here have tried to despoil my threads with-but I don't want to use up all of my slots. How can I get rid of the nasty ones people put on them? I know, some idiots have tried putting on a bunch of nasty ones on them to be nasty-trying to make it more difficult to get rid of them. Please help.