Sometimes we get questions where the problem can't be reproduced given the information OP mentioned.
Sometimes we get questions where OP posts code and asks why the code doesn't work where in fact the code does work.
Here is one recent example I just ran into in the edit queue. However, we've all seen them.
In the example rekire answered the question basically saying "When using your code in an isolated environment it works. This is not the first or tenth time I've seen these sort of answer.
Should users post these sort of answers? Are they useful for the site? Why?
Note: This is not about whether or not to close such questions. I think that's clear.