Best excuse for fogged up front lights?

[Phil74891]

On more than one occasion I have pulled up at a friend's or relative's house in my V8S and after the nods of approval etc etc, the comment has been 'Oh look, your headlights are all fogged up.' followed by the usual 'that's not very good,' 'how much did you pay for that?' type comments.

I have to admit it is a bit embarrassing.........particularly for Aston Martin.

So, anyone come up with a suitable face saving retort? 'They all do that' doesn't quite cut it........