I've purchased eight guns from G/B in just the last 6 months (out of my quiver of eleven) and have never had a problem. Three of those guns I bought 'after' the auction ended (don't ask) at very good prices. Three others I bought immediately when they came up, using the Buy It Now button ('cuz they were smokin' deals). And the last two I won 'fair & square'. All of them have been exactly how they were described by the seller----or better. Hell, at the moment I even have a Hi Standard that I paid for a month ago, have not seen, but is floating around 2000 miles from my house somewhere----'cuz I haven't yet decided where to have it shipped to. Doesn't worry me at all---cuz when I'm ready for it, I'll tell him where to send it. In the meantime though, he and and his son have my permission to shoot the crap out of it.
As far as the auctions themselves go, the ones you are looking at right now (no reserve, started at one cent) are usually good ones. Just put it on your Watch List, know what your max price you'll pay is, and keep an eye on how it goes til the end. And yes, they do have to give it to you at the winning price. On the other hand, the auctions that say No Reserve, yet have both a starting price AND a Buy It Now price that are either fifty bucks apart, or waaaaaay out of line? Those I ignore like the plague, 'mostly because these type of sellers are just waiting to hit the lottery. Unfortunately for them, I'm not their winning ticket, so they're gonna actually have to go out and get a real job soon.
So to sum up, yes, G/B is a great tool---but you really need to do your research first, know exactly what you want, count your pennies, get ready to jump at a moments notice-----and be very, very patient....