Well, just to provide a slightly different point of view here, and I’m by no means saying it’s universal or the only correct one, just my experience living in the Boston area.
The worst laundromats I’ve visited are invariably around the "good" parts of towns, often with dirty, broken machines, lukewarm water (when there is any "hot" water) and people who treat the place as if it was their right to trash it -- they probably, but not always, own laundry equipment at home and only use the laundromats occasionally. Often, but not always, the best laundromats are in the places that have a denser and/or poorer population that knows they depend on a place that is in good working order and clean, so they treat the place with more respect; those places also invariably have plenty of very hot water.
One of the most extreme examples happened many many years ago, I was hanging out with a student at Northeastern University, and he was bitching about having to finish his laundry -- I went along and the dorm had all Miele commercial machines, that the students had no idea how to use (despite directions clearly posted) and were busy trashing the equipment.
Another funny example of reverse stereotypes that I've often seen at laundromats have to do with men/women: often the people who stuff everything inside one washer and run it on cold with way too much detergent are women, who then stuff the things in a dryer or two, dump everything in a bag and flee in a hurry; meanwhile, you look around and see many men separating clothes in different loads, measuring the chemicals and being careful not to slam the machine doors, then they dry and hang/fold everything.
Cheers,
-- Paulo.
PS: as for sorting at the laundromat, I've done that too, but at least I had the decency of doing that in a corner and letting the equipment free until I was ready to go... by the time I was in front of a machine is because I had all the chemicals, coins etc (including sorted loads) ready to go.