I have a theory, not specific to the app store, that there is a strong correlation between customers who are extraordinarily price sensitive and pathological customers. This is based on every software vendor I've ever spoken to saying "After we increased our prices, we dealt with a lot less crazy people -- what's up with that?"

Anecdotally, when I increased prices by 20%, I noticed a marked change in the number of... customers with unique understandings of the world. For example: "I think Bingo Card Creator should print holiday cards. Except, not on my printer, on your printer. And you should mail them for me. What do you mean you don't do that, YOU THIEF, don't make me call my husband on you." (You will run into this customer eventually. A refund and apology is the quickest way to preserve your sanity.)

Specific to the App Store, I think that Apple is training their customers to become pathological customers. From the perspective of the small software developer, "The cost of this app is less than my information search cost, so I'll just buy this app to see if it does what I want rather than reading about it. Bought. It doesn't do what I want?! SUCKS! YOU FREAKING THIEVES!!!1 ONE STARZ!" is just about the worst possible reaction a customer can have to you. The App Store is training people to think of their software in that sort of disposable fashion, but that means you're entrusting your corporate reputation to a lot of people who have one-click access to LOLZ LAAAAAAAME.