My big pet peeve is not being greeted. By name makes me feel appreciated but a cheerful "Hi" or "Good M/A" works too. But I have been scowled at in a certain store--more than once and by more than one employee. As the shop is cramped and dark, I don't feel I'm missing out by not going there.
I also only shop at my local Joann's on Mon Tues or Wed as there's one clerk who is friendly and I'll let others go in front of me just so I can go thru her line.