If I did run a store in the US, my stocking decisions would be made mostly at a lawyer's recommendation. There are a few things I would absolutely refuse to carry, such as any product that I had strong reason to believe contained psychoactives not indicated anywhere on the packaging like the various 'legal pot' mixes with their stealth doses of JWH and CP compounds. I have no problem with compounds I personally choose not to consume, but I have a very big problem with selling deceptively labeled drugs. The guys behind Spice and K2 are just as bad as street dealers selling meth and piperazines as MDMA, IMHO - people like those are one of the big reasons otherwise rational and caring people can support 'hardline' stances against 'drug dealers' and their customers.