I am not sure I agree on the have you got any questions for us. Interviewing is a strange process. I find it quite difficult from being sociable friendly, coming up with decent answers then jumping into some kind of coding question, as it engages different parts of your brain. After you have done that coming up with questions for the interviewers is something different again. I can see why many people wouldn't have anything unless it was prepared. The interview process should be fairly two way anyway, so I ask as I am being interviewed, so often any questions I have are answered already.

If other people find thay have this problem have a couple of canned questions ready. Ask how much of a mess their code base is on a scale of 1 - 10.