I often find myself re-reading my answers just before I post them and asking myself (1) if this answers the actual question or (2) is in anyway constructive. A bunch of times after asking these questions I've abandoned my response.
If someone is continually asking dumb questions that are closed within a few minutes of posting, my inclination would be to write something a little more critical to the poster but I try to balance my critical tone with something constructive that could help the poster build a better question the next time.
As in your case I am always tempted to write something funny as my response but that usually gets edited out by my 2 questions above.