someone in another thread said he thought positive stories about guitar center are few and far between. my personal experiences are otherwise, and we regularly go to five GC stores. my husband and i have probably made 250ish purchases from GC over the years from something as minor as picks to guitars and basses and electronic cymbals. i don't think i've ever had a bad experience from GC, but part of that may be that i have realistic expectations. but we've had a few reps who got to know us - one who really got to know us, and he's the one who made my ric and taylor GC8 possible by letting us make long term layaways (7 months each).
when we were hanging out at various GCs a lot, they were mostly really nice. i got to know a couple guys in west l.a. in acoustics well, and we'd trade playing, customers and gigging stories when it wasn't busy. i admit that the guys from the electric guitars sections are never as friendly, but luckily we don't care
i have heard sales guys at a couple stores mislead customers. one guy told a buyer that he could keep up with a band with a drummer with a 40 watt combo, the other told a buyer that this all-laminate yamaha acoustic was an all solid guitar. sadly in both cases the customers bought the items, and in the case of the amp, i actually told him it wouldn't work, but he believed the sales guy.
but i've heard lots of sales guys/gals not lie, as well. and they can't really lie to me because i never rely on them for any information

i mean, even the most honest person isn't going to memorize facts about hundreds or thousands of items in the store that they've never tried, right?
my used experiences - well, i got an SR500 for $199 and a rockbass streamer 5 for $249. my husband got a used gibson victory bass for a good price in mint condition in 1999 and they threw in a case. my husband got a line 6 amp there for a good price, although we had to wait a few days to pick it up because of the sheriff's department hold. i've never gotten a bad piece of used gear, but the thing is that if i did, i'd call and let them fix it.
as far as selling to GC, i've only done so a few times. a couple, including my luthite cort curbow, i got what i would have sold them for on CL. a couple things i sold because i didn't need them and i wanted the 15% off of a new item that you get when selling them gear. that worked out pretty well.
the worst thing about some stores are the customers. and it's true that over the years, GC stores have failed to stock things i wanted to try and buy including parlor and smaller guitars and lately bass cabs.
i've never had a problem making an exchange or return at GC. they always seem very willing to do either, but i've been lucky and never needed to exchange anything.
without guitar centers, there are so many pieces of gear i'd have never gotten to try and enjoy. they've helped me rule out many pieces of gear. they helped sell me some, too, like my ibanez SRH500, which i'd never have considered without "meeting" one at guitar center.
your turn!