On the other, other hand, you're giving some of his/her customers an interesting, novel experience where they get to feel that their opinion is valuable. Oh, and ensuring that they'll remember that Starbucks far more than most others.

> On the other hand you are probably driving away the customers who can afford to pay for their own coffee and do not feel like being your guinea pig.

Eh? Seems like a simple "No thanks" would due just fine.