I bought a D60 from Cameta Camera off Ebay. It's a factory reconditioned model (supposedly a salesmans model). So far I've done a couple thousand shots with it with zero problems. Saved about $150 off retail.
Also bought my 70-300 VR off Ebay. No problems with that either. Saved about $100 off retail.
I have yet to get burned by Ebay. However, that's not to say it can't happen. Go with people with lots of good feedback and you should be fairly safe.
Most of my cameras (even my other stuff) were purchased used except for a rare few examples. I've had good experience with BH, Adorama, KEH and a few local camera shops. I big plus with these outlets are their return policies (always ask for details) A good percentage of my camera stuff have also been purchased via Ebay and/or direct from individuals. For collectibles, I have purchased items in need of repair and sent them to essexcamera.com for service (they are local to me).
Unlike purchasing new, you have to be a little more critical about your purchases... a little extra caution. Remember.. if it is too good to be true, it is. I never buy from small retailers that are listed with bad reviews on resellerratings.com. Unfortunately, there are just so many scammers out there.
I have heard many people on this site that have bought refurbs from adorama, b&h, etc. and say they couldn't tell it was used. The factories do a great job of refurbishing their stuff.
I wouldn't have a problem with it. I'd be okay with buying used gear from a member on here or another forum, so I definitely would trust the used gear from B&H or adorama.
90% of my photography gears are used. So far, they are mainly from ebay and craigslist.
I had received a lens that I bought from a ebay seller that has fungus even the description said no. But the seller accept the return and refund all my money including both shipping charges. That was nice. Other than that, I really do not have issue with buying photography gears used. And will continue to do so.
As for buying them from B&H/Adorama/Keh. I will not worry about it at all. If the price is right, I will buy from them.
If you didnt tell me the 30D I just bought from Adorama was used.... I would have never even been able to tell! the only thing that is the give away is there is no paint on the edges of the hot shoe... that's about it tho. I couldn't be happier and I saved $140 off of what a new one would have cost. I woudlnt buy a $500+ camera body from E-bay... just too much money when the condition might have been lied about, where as B&H and Adorama can't lie because they have a serious reputation to maintain.
I bought my 1DMk3 from Adorama as a factory refurb. You couldn't tell it from new. I absolutely will buy factory refurb from Adorama again down the road. It's an outstanding deal!