the other thing we can do is to let the shops know when we appreciate the service. The other day someone commented positively on the service in a shop and I copied the comments...without names...went to the shop's website and forwarded those comments to them..again, no names.
When real shoppers get poor service, the first thing they can do is ask for the shop manager and give them immediate feedback (actually do it for good service also)...with immediate feedback, managers can more easily nip the problem in the bud, or get good info for the employees on duty.