We made the mistake of buying a really cheap carpet for hallway and stairs. It is fairing ok on the stairs, but in the hallways it has frayed in most of the doorways - lots of loose threads and looks pretty awful tbh and I really wish I had paid more in the beginning as it all needs re-doing. It started fraying within months of being laid - it was Carpet Rite, not sure if was dodgy fitting or the carpet itself. Think it would only be worth doing on the cheap if you were doing up to sell, but is a false economy otherwise. My parents have lived in their house for 15 years and carpets are all as good as new because they were decent in the first place