cleaning a throttle body

Some people say spray with the car off some say spray with the car on. Anyone know which is best? I 'd imagine a warm running car would be best. but who knows?

I think spraying a warm, running car would be best. Popular Mechanics had an article about this not too long ago and they advise not to spray the body with any substance that has silicone in it. Like WD 40. It will coat the O2 sensor and ruin your mileage. I think regular carb cleaner would be all right, though.