I can totally sypmathize with you and completely understand your frustrations!

I've worked with the public more than half of my working life, including a laundrymat and a grocery store on a midnight shift. Talk about some WEIRD rude people on a graveyard shift! We had a creepy crossdresser who didn't shave off his beard, which honestly clashed with his stuffed bra pink sweater. And the unshaven male legs in the black nylons clashed with the black split skirt and tennis shoes! I had a guy call once at the store with a baby screaming in the background, the guy cussed me out every which way because his milk was spoiled and his kid wanted some cereal. I've had drunks trying to do laundry, and hoity toity fussy people who look down at their nose criticize how their dry cleaning was bagged when they picked up their clothes. I've had where I work now someone come in to buy Frontline Plus and I explain to the guy how to open the package and use then an hour later his wife comes in with a totally massacered package saying it was 'empty' when she finally got it open (despite the oil all over the package) and demanded a free replacement. She didn't like it when I told her I couldn't do that and cussed me out 3 ways from tomorrow. I've had customers whine about our prices (which are low for the area) and claim 'poverty', gripe, and complain all while they are in the building only to get into a brand new caddy, pt cruiser loaded, or avalance when they leave.

So YUP, I totally understand the frustration. Best you can do is rant when you can, smile when you should, think of all the things you'd like to say while the person is ranting and grin thinking of how they'd react if you said it.

If that doesn't do it, and you think you've had a really bad day dealing with customers, try this website....
http://www.customerssuck.com/

It always makes me feel better about the customers I have to deal with sometimes and realize it could always be worse.