Adding to what has already been said:
Usually if someone thinks the bug has a factor making it unclear, invalid, or questionable in some way, a developer or TAC staff member will comment and ask for more info, close/reject it, etc. We're not usually shy about asking for more detail, method of reproducing the bug, and so on.
The fact that it was left as-is can sometimes (though not always) be taken to mean it was potentially valid or at least sufficiently clearly described and it needs someone to look at it, investigate, get further confirmation, that sort of thing.