I was denied purchase of a tube of model glue at a hobby store some years ago. Presumeably, they suspected it was my intention to huff it. Not so - I really did need it to make a small repair.
However, they had no problem with selling me twelve Estes D-class rocket motors, which I was buying so that I might crush them in a vise, and harvest the propellant for use in the construction of less-than-legal pyrotechnic devices.
Hm...wonder what snorting pyrodex would do to the old nervous system...