Smoking gives you cancer, drinking ruins your liver and can result in uncontrolled behavior (brawls, DUIs, etc), and tattoos basically ruin your chance at a lot of jobs.
Your argument is that something is fundamentally bad if it can be harmful in excess or will be used as judgement against you. A basic application of this rule damns water and atheism.
They're also all correlated somewhat with anti-social behavior (of various kinds) in general, which I think was the point the mother was relying on. "Because he lacks traits correlated with bad behavior, he must not have engaged in bad behavior." Obviously, this is faulty, but mothers often aren't rational when it comes to defending their kids.
If the quote block isn't sufficient, I should clarify: I am commenting on gnasher719's statement, not the mother's.