If he's folding 70% of the time to cbets, then I cbet him every time with my entire range. If we have AA here, checking is going to look rather suspicious if we've been firing 70% cbets at him every other time he sees a raised flop with us. If we have a strong hand, then hopefully he loses patience with us now; if we have air, then hopefully he won't. But if he raises our air, fine, we're still running at a profit if he carries on folding 70% of the time. If he folds to our nuts, whatever, he had junk and was folding it as soon as he could.