“It is really nice that you want to help your friend, but it isn’t a great idea. There is a way that this plan can backfire on both of you.
In Dave’s case, since he is knowingly lying about his address, this would be called material misrepresentation. If his insurance carrier finds out that he is using your address, they may give him a chance to correct it or they could cancel his policy.
Most carriers use public records to verify addresses and see if any other potential drivers are in the household. Since Dave is using your address, your carrier may require him to be listed on your policy. For him to be removed, you would need to prove that he doesn’t live there and send in a copy of his current insurance policy.