The out one sometimes has a valid use, although it could be name better, as in out-parameters.
For the other cases, it appears as those some people still don't understand what tags actually are, and in the case of your example they decided to just use an abbreviated summary instead of actual keywords.
To the new user "cache timed out" makes perfect sense to him, as it is descriptive of whats happening to him. To those who understand that the phrase is then broken up into three different tags, "cached", "timed", and "out" then it makes less sense, and hopefully someone will retag it to something like "cache-timeout". I'd just let the community worry about the cleanup, and when you hit 500 rep then you can do the same.