great in some ways questionable in others

I don't trust what they sell, why would two of the same beds (make and model) feel completely different? Why would the bed you ordered feel just right in the store but at home it is too hard. Or a bed that looks ok but after you try to sleep on it, you realize that something is wrong. The bed is like a hill, crowning at the top, sides sloping. I feel totally defeated and sad that I've wasted so much money.