We haven't had issues either, in any of our trips. The vendors @ Union were much more aggressive than at the Cays, but still pleasant and no one minded a pop, beer with a refusal.

We always pick one vendor and stick with him during our trip. He arranges another vendor to come if he doesn't have what we want, and we tell all the others that we're dealing with so & so.

I've had some great conversations with them over a beer, and nothing purchased.