What is the most expensive thing that you purchased that made you subsequently feel that you had been cheated?
I would have to say that it was an Acer computer. I don't remember what I paid for it, but this was back when computers cost a whole lot of money, so buying one was not an impulse decision. The darned thing barely worked when it was new. It took forever to boot up, and every action with the Acer was so much slower than the computer it was supposed to be replacing. Then, when it was less than two months old, it crashed during an OS upgrade. When I tried to return it under warranty, I learned that installing a computer program - any program that didn't come with the computer - voided the warranty. That's a little like buying a car only to learn that if you drove it off the lot, you voided your warranty. After going back and forth with them, I ended up buying another computer, not an Acer, and I have never bought another Acer again, and stripping the Acer down for parts to use on a computer that I was building at the time.
I have a lot of buyers remorse which is not the same as feeling cheated. Just feeling foolish, Like, HOW COULD I HAVE BOUGHT THIS?!
I finally thought of something. The first roof job on the house. (The word "cheated" was the stumbling block.) They didn't put down a drip edge. They promised to use 5/8" decking, but ran out and finished with 3/8". The did some carpenter work on the back dormer and used pressboard siding instead of wood or cement board. It swelled and rotted very soon. They missed nailing a few of the shingles, so they slipped out a few years later. I knew about the 3/8" sheathing because I saw a stack of it. And of course I could see some shingles sliding down a few years later. But the rest of it I only found out when I got the second roof job. The new contractor wasn't lying. He showed me.