Some that i have come across:
The Know-It-All: These people will, invariably, know everything there is to know about the product, but will still want you to explain it to them, usually pointing out any flaws in your knowledge. Unfortunately, they are usually wrong but don't want to admit it. (Their previous machine had a two megabyte processor, as a matter of fact.)
Remedy: There isn't one. Either they will buy it or they won't. You are just wasting your breath trying to give them more information on the product. However, make sure to correct anything they get wrong, but do so politely. This prevents them from coming back later because "you sold them a defective product" because that cd player they bought cannot play mp3.
Sales prospects: Medium. If they're there, usually they want it. However, a lot do come just to chat.
The Brat: Surprisingly, is not usually young. Will want the most expensive item in the range because it's the best, but wants to pay a midrange price for it. Will also treat you rudely and answer their phone whilst you are talking; "Oh hi Sharon. No, I'm not doing anything. He said what?" Basically a schoolyard queen bee who never got taught how the real world works.
Remedy: When they are on their phone, walk away slowly, and be helping someone when they get off it. If they stand and stare at you like they should have your undivided attention, just keep giving your new customer your attention. If they are still there when you finish, go help them. There isn't much else you can do.
Sales prospects: Surprisingly good. Usually the reason they never learnt to grow up is that they have had a Gold VISA since they were 15.
The Donator: Even if they are purchasing a small, inexpensive item, they will want more off the price because they've "spent heaps of money here, and are good customers." Note, the ones who are genuinely good customers are not to be included in this category. People in this category are the ones who bought a $50 toaster 2 years ago.
Remedy: Just ignore it. Repeat what you told them before, and wait for their reaction. They will rarely get irate. If they do, point out that you can look up their purchase history and find out what they spent.
Sales prospects: Good. Most often they will purchase the item anyway, no matter what price you tell them, because they want to feel like a good customer. Some will walk out on the sale, but you're not going to give them a discount on that $20 ink cartridge.