I recently removed the [json] tag from my Interesting Tags on StackOverflow because the majority of the questions marked with this tag have very little to do with JSON itself (example: REST / SOAP endpoints for a WCF service). I know plenty about the nuances of JSON parsing, and a little bit about its typical usage, but questions like the one I linked do not pique my interest, and there are a lot of them.
Hence, in my humble opinion, the [json] tag on StackOverflow is currently what I'd call an "ill" tag, as most of the questions (perhaps more than 80%) have very little to do with JSON. On the other hand, the [c] tag appears to be "healthy", as most of the questions are actually about C. I speculate that the vast majority of tags on StackExchange are "healthy".
Has anyone else encountered tags like this? Again, I'm not talking about tags where the occasional off-topic question pops up. I'm talking about those tags that highlight unrelated posts consistently, to the point where it's annoying.
PS: The json tag doesn't really belong on this question, in my opinion. I'm using it to prove a point :-)