Landlord refuses to part with '70s shag

What's the normal life expectancy of carpet?

Q: I rent a small cottage and have some concerns about my carpet. It’s the kind of carpet that can best be described as 1970s-style shag with all the different color browns so you can’t tell where there are spots and stains. I hate to think about what stains could have happened in the last 30 years! My landlord promised to replace the carpet before I took possession of the rental, but when it came time to move-in he just had it "cleaned."