I think both the cash and the cue have to go through escrow. The bum check scenario doesn't bother me because the escrow company shouldn't clear the cue for shipment to the buyer until the the check clears or otherwise good funds are in the hands of the escrow administrator. What bothers me about direct shipment of the cue to the buyer is what if the buyer says he never received the cue? Or he rejects it and sends it back but the seller never receives it or says that he didn't? Yes, I know there is tracking and the delivery can ultimately be documented but what a nightmare that can be avoided if everything physically goes through escrow.
The big problem here is shipping things to other parties, as opposed to just handing it to them. Anyone can say "I didn't get it" no matter what it is, and be lying. And there's not much one can do to call them on it or do anything about it.
Shipping confirmation? "Oh I never got that, I didn't sign for it - it must have been misdelivered" or "No, you got my address wrong, someone else got it" when they arranged for that to happen... any number of ways to game the deal.
Add to that the whole condition check/authentication end and the headaches exponentially multiply. What if the guy checking the condition has one opinion, a differing opinion than the guy who ultimately receives the cue? What if the guy who receives the cue is unhappy for other reasons and decides to try and make the cue's condition (and the report thereof) the reason he's unhappy?
Basically the guy offering that service is opening himself up for hassles - and they'll come one day, believe you me. Someone will be upset and will make a stink. And when it comes down to having two people to blame - a scumbag and a stand-up guy who was trying to do right - they'll go after the stand-up guy more often than not, because they figure they'll get what they want from him sooner than they will from the scumbag.