precisely the reason why I never buy a used motor unless it is in the car and startable or has been rebuilt and I can talk to the person who rebuilt it. (or if it's on a stand and hooked up to run). I have absolutely no faith or trust in other human beings, and so far this outlook on life has saved me lots of money.
Sucks that you got burned on a motor. It happened to me once back when I was 16 (young and stupid) and I bought this black rabbit with a supposedly blown head gasket that was supposed to be an easy fix. Turns out the cylinders were so worn that the walls had deep grooves in the tops of them (engine needed re-sleeving), the head was warped, and the entire engine was full of coolant, which had been sitting in the bearings for about a month, completely rusting them into worthless garbage. The engine was a complete loss. To top it off, the car had been in an accident some time in the past and had been "fixed" by someone who didn't understand geometry, and the body was not straight, so the tires were badly worn (I thought at first it was alignment until the guy at the shop showed me the creases in the underbody). Since then, I've never trusted anyone who is selling me a used car, a used car part, or a used engine.