Well I don’t have a pet (landlord doesn’t allow them) so this is a very tough one. But here is what my last dog hated more than anything else. Gorgonzola cheese. My dog was a very trusting animal, and loved us completely. But after the one day we gave him gorgonzola cheese, he smelled everything that came from hands after that. He never looked at us the same way again, I think. So note to all dog owners, don’t give them gorgonzola, they will never trust you again.