Well, I've bought two used Ampeg PN-410HLFs from GC. One was in LA, the other is in OH. The one from LA. was a ridiculously low price, so I figured it was pretty beat up. I called the store and they confirmed that it looked like crap, but it worked fine. I bought it and had it shipped to me. I got 2 days later and it did look like crap, but it did sound great. It was, however, one of the worst packing jobs I've ever seen. I am surprised it survived shipping.
For the astute who noticed that I said my second one "is" in OH, I bought it last Friday. It's supposed to be in better shape than the first one I bought, so it was a bit more expensive. Supposed to have shipped out on Monday, but it seems to have gone missing. Not GC's fault, but they use UPS, so it's kind of GC's fault. I'm not-so-patiently waiting for a resolution.
I don't mind buying from GC, as long as they are being accurate with their descriptions. The return policy works if you have it shipped to you or the store, so it's just a matter of ship it to me and hafta return it to the store or ship it to the store and hafta drive there to pick it up...