You can get that kinda treatment in any store , go into a store & let the owner/employees know your buying booze or tobacco for a minor & they wont sell to you .
Go into a gun store & tell them your gonna do something illegal with the ammunition & you'll be refused service , it applies to all stores where their product can be used legally or in an unlawful manner , its just the business owner looking out for his own ass , when i owned the co-op members would say stupid shit like " Man Bob's gonna love this shit " or " This shit looks killer , its gonna have Sue all fuked up , ignorant shit like that & we had no choice to refuse them service , same as telling the pharmacist you plan to share your meds or abuse them , it isnt really all that hard to think before speaking .
I wouldnt be angry at the shop keeper if your in an illegal state , shops that sell paraphernalia are scrutinized like a mother fuker to begin with .