I've never returned something because of buyers remorse (I don't purchase something unless I've thought about it for a very long time, and have the money for it) but I will return items when they are broken.

For example, Costco's return policy is absolutely amazing. I purchased an air bed from them and after sleeping on it (ahh, being a college kid) for 7 months one of the ribs holding the form together broke and it had this weird bubble in it. I brought it back to Costco, and replaced it with another one.

I don't abuse it, but I don't think that a product should have to be replaced at 7 months in. I've done the same thing with a foam mattress I bought from Costco, after sleeping on it for 2 years the manufacturer refused to replace it even-though there was a huge "dent" in the middle so that sleeping on the bed meant you rolled into the middle automatically (made it uncomfortable to sleep with my girlfriend, now fiancée). Brought it back and we bought a mattress with springs.

The amount of money I've spent at Costco far outweighs the cost of them doing the replacement for me, and the cost for dealing with the manufacturer.