I am not so mean as to name them. There are three main reasons for dropping a store off my list of shopping-for-games places.
1. Failure to stock
If I can't find the game I want everytime I walk into a store, I'm just going to go somewhere else.
I don't want to have to call to check first. I don't want to have to preorder stuff every time because I expect current releases to be properly stocked. I don't want to have to come back some other day. I don't want to have to do all that work when I can walk into a store and buy it off the shelf.
(To be fair, in some cases, especially popular and hyped up titles get sold out pretty quick and if you want to get them on the first day, you must preorder.)
If another shop has it, I will buy it from them. If X or Y shop can stock up properly, I don't see why you can't.
2. Playing your own game, ignoring the customer
I've seen staff that are so engrossed in their game, they hardly notice that the customer is there or that he has left. I suppose ignorance is bliss.
There are also staff who stand around like statues, starring into space. (I don't like to be hounded, but I don't like feeling like I'm suddenly a ghost.)
3. Recommending crap to customers
I'm quite knowledgeable when it comes to systems, games and accessories. I read a lot online on the stuff I intend to buy and hang around on game forums gathering opinions on titles I may or may not have an interest in. I do know if a shop staff is trying push something crappy on me.
And I have been known to yank other customers out of the store if I overhear a staff giving the wrong information.
I don't believe in shop loyalty. If I find that the shop I've been buying stuff from for more than ten years has hired a bunch incompetent types and that the service has declined, I will shop somewhere else. There really isn't much of a difference in terms of game prices between different shops these days, so it's really no lost to me.