If you can test ride it and it feels ok, $40 is not much of a gamble. Anything you buy for $40 is going to have substantial issues that make it a gamble, so I think that's the only reasonable approach--try it and see. If you can't try it, don't buy it. That's probably your answer on rideability right there. When people won't let you try stuff, it usually means they're trying to charge you to take out their trash.