My biggest gripe about my local GC is the setups. Not that I would pay someone else to set up my bass. But I've fixed several incompetent GC setups for friends.
Also, they tend to have one or two graybeards who actually know what they're talking about, and a bunch of high school kids who'd be better suited to flipping hamburgers. But what can you expect from a corporate chain?
AND, I can remember one time going in to try out amps. I brought my main bass, a beautiful Carvin LB76W. Those of you familiar with Carvins know that they don't have model numbers on them, they just say "Carvin". The kid at the door had to "check in" my bass, which involved writing down the make and model. Now, I'm pretty sure this was a good kid, and he handled my bass carefully, but DO NOT take my $1600 bass out of the case and start turning it this way and that looking for a model number. I will kill you.
Actually, I was cool about it, I just gave the kid the model number and told him (nicely) to put my bass back in the case. But I was chatting with him later, and he wasn't even a musician. He said he was interested in getting a setup to DJ for hip-hop type stuff. Why is this kid touching my bass? My local mom-and-pop doesn't make me go through a "checkpoint", and everyone who works there is a musician.