Selling RV for smaller one

They should clean it the best they can, but list it as a smoker's TT that has been cleaned. I can detect cigarette smoke a mile away, no matter how small the amount, and I get an almost instant nauseous headache when around it.

It's an 04, not going to bring a lot of money anyway. Advertise it as a project trailer and get what you can.

If you had to tell them to not smoke in the unit after it was cleaned, I'm guessing they are heavy smokers.
Like others said, don't waste a lot of time cleaning. I would advertise it as a smokers RV.
No matter how well it is cleaned, most people will still smell it.

Just put a Ozone machine in it to kill the smell.

I would just discount it heavily and not put a lot of work in it. I would disclose everything. There are always people looking for bargains.

:) Hi, you can make it better, but you will never make it good. Best to let buyers know the truth.

CLR for the shower doors.

For the smoke, that's a really hard one. Cigarette smoke is very difficult to eradicate - and there are people who are so sensitive that even the slightest remnant can trigger breathing issues.

I would use a good solid cleaner - chlorox, pine sol, etc. for all hard surfaces. I would rent a rug doctor for the carpet (the household carpet cleaners and/or home use machines are not as powerful as the rug doctor). I would wash any cushion covers (or use the rug doctor on them if they can't be removed) - same with the blinds. I would remove all cushions, mattresses and blinds and let dry out in the fresh air.

Then I would use something like Natural Remedy to spray throughout the RV and then open all windows and let air out for several days (the longer the better).

In the end, I would not advertise as "smoke-free" no matter how good it appears, and if someone asks, be honest and say "Yes, we did smoke in it. This is how we've cleaned it up for sale..."