You have the best shops near you, Donna. Or maybe it’s just you are very good at seeking bargains out. I have found some great things in the TK Maxx near me - last good one was a 400ml bottle of Decleor Gradual Glow for £16 - but generally, it seems to be a lot of brands I’ve never heard of or slightly tacky-looking things.
I don’t know about other people’s local TK Maxx shops but mine is full of stuff that has been opened and tested. You have to get there either just after it’s been put on the shelves or find one in a hard plastic security pack. You see people just blatantly picking boxes open and pulling out the contents to unscrew or pop open to smell, spray, swatch, etc. They are not even subtle about it. It happens in Boots and Superdrug (probably everywhere) to some extent but never that bad.