I'm not familiar with waste bunkers or waste areas (although I have been to bits of London that might qualify as the latter...
). Do they have bunker-like sand? Interesting idea as it would clearly remove any ambiguity. Can you make practice swings and 'test the surface'?
If they're not raked, you could get some nasty lies in the last group. Or would they try and mess them up in a uniform way? Maybe get a couple of excited labradors to run around in each one for a couple of minutes.
I've also always wondered how you know if you are in a waste bunker as opposed to a bunker bunker. I've played from sand up in the dunes on links courses that were clearly not bunkers (where you can ground your club... with the risk of improving your lie), but they have never been called anything. Do you think that even if Dustin was not technically playing from a bunker, people would have been saying that he improved his lie and (perhaps) won the USPGA unfairly?