I don't have too many stories about lazy/incompetent/asshole sales clerks, and frankly I don't think that matters, since you find that just about everywhere you go nowadays. I'll just give a few examples of why I don't shop at GS:

1) A few Xmases ago I went in for their B2G1F sale. After spending an hour trying to find three games I wanted at what I thought were reasonable prices and were around the same price, I took them up to the counter. They (including the manager) could not find one of the games' disc and only offered a "go to another store" by way of help. Really, out of the three games I was intending to buy, I really only wanted one of them pretty badly: Tales of Symphonia: Dawn of a New World. I left disgusted only to walk across the street to Best Buy (never the bastion of cheap prices) and find the game new for the same price GS wanted for it used.

2) My friend bought me Devil Summoner 2 for my birthday or Christmas or something, but the corner had a dent in it. So I took to to GS to exchange it. They had several copies but each and every one had some defect. I ended up just keeping the one I originally got.

3) After hearing about some of the great deals GS advertises for games on their website (that can only be purchased in-person in their store), I went specifically looking for some of them. Of them, PSO I+II for the Gamecube was the best deal I'd ever heard of. Come to find out, no GS sells this game b/c of its online component. They don't take them in trade, so they never get them, all b/c you can't play the game online anymore (never mind that the game is perfectly playable offline).

I just give up. Their prices tend to be higher (sometimes twice as high as) online after shipping, and that comes right to my door. Why should I bother?