For the record, yeah it takes the old school trust method. In my few times we've generally spoken on the phone a few times and of course additional pictures, etc from the standard stock photo in the ad to confirm they have the item. It's not something I do that often either since yeah there's risk but I don't know how much riskier it is than any other auction. One of you gets to pay first and the other has to hope things work out and noone is a scammer or pull the payment afterwards, etc. I've had pretty good luck here and there though and have been pleasantly surprised with folks being ok with the shipping offers (although I suppose I get the majority of no replies also but that's even for local CL ads).
You somewhat have some protection though if you're going through paypal, etc. Ironically the Pet I bought was completely old school lol and was both of us talking, a few nice pictures by request, then a money order and tracking shipment and hoping it isn't just selection of their finest area bricks.