Only time this is an issue if someone is covering up a problem that exists.
Otherwise it's an open market. There are always good deals to be had if you want them, you just have to keep your eyes open and you'll get what you're after.
Plenty of people do this flip for a profit on all sorts of items. I've had a go myself with varying degrees of success. Unfortunately I wasn't that good an lost more than I made as sometimes the item would be worth more, but the cost of parts would eat into the profit. But I was only doing it for fun and once I ran out the small amount of money I was playing with for it I moved on.