If there is something you just don't do to an independent coffee house, then it is to come into the establishment drinking Starbucks. Ok, sure, you purchased something, but sitting in a good coffeehouse while drinking McCoffeehouse brew is a sin to the coffee gods that can't be forgiven.
I am witnessing said act as I type. The two women are sitting very snobishly at the next table. If they don't gag on their quiche, it will be a miracle.