I have a Bissell carpet shampooer that I bought refurbished on Overstock.com 6 or 7 years ago. I don't think there ever was anything wrong with it. Whoever returned it probably just bought it to clean their carpets and returned it. It still works. It's been having a problem where the detergent won't feed out of the holder any more, but I can get around that by putting vinegar in the hot water tank. It still does an excellent job cleaning.
I'd have to agree about lending it out. I lent mine out to our friends down the street and the detergent feed problem started after that.
Jill