I agree. A lot of times people sell things for a low price because they just want to be rid of it. We have had 3 refrigerators over the past 33 years in this house. The first one was purchased for $75 from a private party (I'm guessing we found out about it from a classified ad). That lasted probably 10-11 years.
The second one was purchased from a guy who lived in the neighborhood across a busy 4 lane road from us. We paid $50. My son, with his new driver's license, drove across that busy road with DH in the open trunk of the car, dragging the fridge which was strapped to a dolly. That refrigerator lasted about 15 years.
The third one was purchased new, as a floor model from Lowe's, in 2012, for $800. We have already considered replacing it because we've had to have it serviced 3 times already. Buying new can give you false confidence.
So, really, you never know when you buy used stuff, but we have been pretty lucky.