I agree, it's bad form to order a record and then renege on purchasing it - it's even worse when the person won't make a simple phone call or send an e-mail to the dealer to let him know that for whatever reason they can no longer meet their commitment to buy. It must be frustrating being a dealer.
On the other hand - I've had quite a few situations where I've ordered records from dealers, been told that they're on the way only to then find that they've mysteriously disappeared from their stock systems. Only to reappear a few weeks later with a heftier price tag.
The fact that a lot of these records were beginning to get played and were listed for less than you'd reasonably expect to pay for them was obviously unrelated.
I've also heard of another situation where an e-mail was sent, funds exchanged, the record was packed ready to go out, only for the dealer to accept a significantly higher offer for the record from someone else. The dealer was apologetic, but quite open about the fact that he'd had a better offer. A sort of "Sorry, but screw you" attitude.
So I guess it cuts both ways - I know it's ultimately the dealers decision to sell for whatever price they want, to whoever they want, but I know I for one wouldn't buy stuff from those particular dealers again.