The fail tag is fail - how meta is that? And I'm posting this on a meta site. It's meta meta meta.
fail offers no benefit. It's not likely to be searched, it does not distinguish a question's content or help people find answers or discover questions to contribute to.
##EDIT 1
I argue that fail in and of itself isn't enough of a modifier to really help in the search for posts. With a name like ServerFault I would bet that half of all posts (at least) would be strong candidates for the fail tag. Now specific failure as tags would be awesome.
- 503-error It's real! Click it!
- permission-denied It's real! Click it!
- error-5 Not real.
- access-denied It's real! Click it!
Is it something of a recurring tag? I don't think it's too terribly recurring, no. After two years we only have 13 survivors. Once a year we could sweep through a list of tags like this and kill them dead.
The nicest solution IMO would be to blacklist it. Think we can convince the right people? HAW! HAW HAW! wipes tear I'm so crazy sometimes.