Glad to see some action to get rid of these creeps. It would be nice if local police would make a friendly visit to some of these people, so that they know their actions online can have real consequences.
Regarding scammers, one of the funniest threads I've ever read is here: http://www.zug.com/pranks/powerbook/
I've bought and sold a few things here. I've been pretty careful and would generally check someone out by checking their work email address, web page, linkedin, ringing via work reception to confirm they work there, cross referencing the invoice address or once checking on google street view that the building looks like a bike shop. Mostly when something looks too good to be true it is. Other than some "ambitious" descriptions - i.e. These wheels have only done 200km" yet when the wheels arrive it's pretty clear that the rear tub has done more like 2000km. But ebay / car sales people can be the same.
If you're based in London I'd recommend using LFGSS to sell things (even old knackered things as long as they are top of the range or campag) - lots of people there who can deal face to face and generally pick things up in 1-2 days.