I've had very good luck with CL so far. Sold a couple of point & shoots, lenses, cell phones and a monopod to a cop who showed up in uniform in his police car, paid cash and left. Most recently I sold my 50D to someone who wanted me to meet him closer to where he's at (45 minute drive for me) and he actually paid more than I was asking to cover gas.
I'm surprised that I haven't sold my EF-S 10-22mm yet (lots of lowballers though) since I listed it at the same time as the 50D body. I was confident the demand for the lens would be much higher than a 4-year-old camera body. Haven't got lucky yet.
I hear what your sayin. It's suprising what sells and what doesn't. Apparently the Canon 17-55 is one of that doesn't sell!