Yeah, it didn't smell but we hired a rug doctor and gave it a good wash. All this was 15+ years ago.
Mind, given the general standard of private furnished rentals me and my friends had in the North in the 90s, I can't get over-concerned about a lived on carpet.
Need a proper good shampooing as you have no ideas what have went in it.
We ripped our out the moment we got the keys as it a horrid white and smell of wet dog.
Sanding takes ages but doable, do it yourself can save a whopping £200 each room.