I work for a rather well-known retail chain that shall not be named here (hint: it ends in -ears), and as such, I've come across the gamut of rotten customers to deal with. Ever wonder why some salespeople seem surly compared to your cheery demeanor? This is why.
If you're thinking of hopping into retail/sales, please consider this a primer for whom you are going to be dealing with; training videos and computer seminars never mention these people, but they are there, in DROVES. There's also a chance that you may be one of them; if so, please change your shopping style. Thank you.
If you work on commission as I do, I've noted the likelihood of them buying whatever products you're selling.
There are several types of terrible customers, as follows:
Intimidators - These guys will stop at nothing to get a deal. They want something for nothing. If a television is priced at 500 dollars, they want it for 350, nothing more. They think every purchase is taking place at a garage sale, and as such, expect to be haggled with. Refute their "generous" offers, and they become angry, aggressive, sly, loud, or all of the above. They usually drag their significant other along with them, possibly as a means of showing how much of an Alpha Male they are, beating their proverbial chests. They will want to talk to a manager if you refuse to budge in your insistence that, indeed, 500 dollars is the price they are going to pay for that television, hell or high water.
Remedy: get your manager, and ask them to say the same stuff you've been reiterating to them for the past quarter hour. They usually back off when a Higher-Up tells them that, indeed, the television is on sale for 500 dollars, have a nice day.
Sales prospects: Low. If you don't buckle, they don't want to do business with you. If you do give in to their demands, they'll keep asking lower prices and better deals until you cry, because they've found a chink in your armor. If they act like they're going to "walk out and never come back", tell them to have a good one; they RARELY walk out on you, as they still want to haggle and get the best deals. However, it would be best if you just walked away from them and avoided wherever they stand in the department.
The Endless Talker: You wonder how long they've been without social contact after about 5 minutes of talking to them. Ask them for help, and you will be ensnared into a three-hour long ramble on the State of the World. They don't want to buy; they want someone to talk to. And possibly a hug.
Remedy: Show them the product they were originally looking for, and walk away. Quickly. Pretend you are deaf and mute. And anti-social.
Sales prospects: Low. The potential is there if they actually came in to buy something, but if they waste your time for a long stretch, you're going to lose 3 or 4 more potential customers who got huffy that they didn't get any service. It's better to keep eye contact and slowly slink towards the break room/bathroom/wherever, and tell them to have a good day, and walk out of sight. They won't follow you.
The Confused One: Usually elderly people (note: I am NOT implying that all old people are confused and annoying, don't even go that route) or persons who don't speak much English. They have little idea about how your products work, and as such, require lengthy explanation about rudimentary functions (such as a compact-disc player) that should already be common knowledge.
Remedy: If they still don't grasp whatever concepts you've explained to them four times, it's best to just walk away.
Anecdote: A friend of mine was helping a couple look for an alarm clock/radio. After exhausting every possible model that we had on display, and explaining to them the benefits and disadvantages of each, the couple finally widened their eyes and walked briskly to the end of the aisle, exclaiming "aah, now this is perfect! It's got a cd changer, a tape deck, it's nice and small..."
He had found our old Packard Bell computer system that was set up to look for car stereo equipment. The cd changer was the cd-rom drive; the tape deck, the floppy disk drive. And nice and small it wasn't; it was a full-sized tower, circa] 1994. Needless to say, my friend walked away, shaking his head slowly.
Sales prospects: Medium. If you can get them to understand the advanced concepts of the 20th century, they might like you well enough to buy it. Pray to the gods.
My Penis Is Large: These customers will walk in, and stare at a big ticket item for at least 10 minutes. When you ask them if they need help, they inform you that they have purchased this big ticket item already 3 months ago, and immediately begin regurgitating the sales pitch he got back AT you. Essentially, they are bragging to the salesperson that they can indeed hand their credit card over to be swiped.
Sales Prospects: On a scale from 1 to 10... -5.
Remedy: A swift kick in the face. That, or a lengthy discussion on the extended warranty they didn't want the first time around.
The Bargain Hunter: A subset of the Intimidators, these customers almost invariably have a week-old sales ad in tow, followed by at LEAST 1.4 kids. They immediately demand your out-of-stock bargain-of-the-day. When you tell them that they are a) a week late, and b) wrong on the price anyway, they then demand to talk to a manager.
Sales Prospects: High, but you won't get more than 30 dollars out of them.
Remedy: A Day After Thanksgiving stampede of customers. Hopefully they'll trample the weakest ones, thinning the herd.
This is not yet a comprehensive list. More types added as they are encountered in the wild.