For example :
The copyright tag.
95% of the Questions are closed as off-topic.The other 5% also being off-topic (but not closed) despite of being equally off-topic.
Bad tags exist because anyone with sufficient rep can add tags. It would be nice if they only added good ones, but that's not the world we live in.
If a tag is sufficiently bad, and sufficiently persistent, it can be blacklisted to prevent its further use. copyright may well rise to that threshold, but I'd be curious about how persistent it's been and how consistent an indicator of a bad question it is.
This is actually useful, even in cases where not absolutely all such questions are offtopic (maybe
latex are examples of this - most questions are offtopic, but theoretically there could be questions on them that are actually about programming). That's because people so motivated (such as myself) can follow the tag and pounce on such questions to catch bad questions earlier!