I take it you don't smoke.
My family doesn't, but my dad replaces carpets.
1. This is a gradual thing, and probably unnoticeable over the course of years.
2. It's an addiction.
It's not as bad if you only smoke outside. But it does come in on your clothes and your skin and your hair and it gets in the furniture and the carpet.
Had the same thing happen in my last house I moved out of, and nobody who lived there smoked. That happens with any carpet that isn't extremely thoroughly cleaned regularly, Smoking does cause it to happen faster though, and affects much more than just the carpets.
My family doesn't, but my dad replaces carpets.
1. This is a gradual thing, and probably unnoticeable over the course of years.
2. It's an addiction.