Especially if you are unsure about the person's view on drugs or experience with them. Puts the person in a awkward spot. Had the guy done cocaine with Tony before, it wouldn't seem as kind of scuzzy as it does otherwise.
Cocaine is a weird drug, because it's psychoactive effects on the brain are almost in perceivably subtle to an observer, like it was for Tony. Unless they've been on a 8 hour binge. But a toot or two of cocaine is fairly benign, IMO.