I just say "does it look like a kit?". If they say yes, I just ask "really? What about it brings you to that conclusion?" Of course I am smiling and sincere the whole time, but 90% of the time, they say that it doesn't look like a kit, and the other 10% of the time, most can't tell me why they think that. In the end, I usually tell them, but then I get compliments on the things I have done to make it look period correct, etc. It's a more entertaining exchange than yes or no.
