This is not precisely a problem in my opinion, but I still think it should be addressed.
We very often see poorly worded questions here. (I asked a lot myself). It's well known that to ask a proper question one has to know half of the answer.
Usually, the community is happy to point out obvious errors and unclear points in the comments.
But sometimes, people give answers which utilize the 'weak points' of the question, even when it's obvious the OP was asking something else entirely.
I don't want to give examples, because there can be controversy for every particular question interpretation.
What I think about this tactic:
1) It's useful, because people need to learn how to formulate mathematical problems properly. Also, sometimes a 'trick' is expected for a particular question, and not a 'straightforward' answer.
2) It's not always good, because such answers will most likely be upvoted by the community and might discourage other people from giving more complete answers to the real question.
What do you think?