In my experience people are pretty good online and on craigslist as well as ebay. I've bought/sold at least 10-15 cameras and lenses on craigslist, ebay and my photo forum. Plus tons of ipods, high end headphones (over 600 dollars each). My 70-200 f/2.8 that I bought recently? Was off craigslist too.
This one.
All the camera bodies I've owned were sold on craigslist. I think it's pretty safe to be honest,
as long as you meet them, try it, etc. On ebay it's pretty secure too since you can make a claim with paypal if you don't receive your item.
Since I work in a photography store, I've known so many people both staff and customers that have bought/sold cameras and lenses on craigslist with absolutely no problems.