(as) crooked as a dog's hind leg

Very unscrupulous and deceptive. Paul's never run an honest business in his life—that guy is as crooked as a dog's hind leg. I've always known Ben to be crooked as a dog's hind leg, so I'd steer clear of him if I were you. The company is likely doomed now thanks to this exposé that their CEO is crooked as a dog's hind leg.