I've bought a bunch of stuff and been "had-bad" once or twice, but overall, I am way ahead. Accept the fact that you are taking a risk, minimize them by applying the principles explained in the previous posts and you will save some money. But accept the fact that eventually, you will get burned.

I bought a TT PRO-46 that was listed as being from an estate sale, so the the seller had never run it, but said it spun freely and had good compression. He didn't really know the engine, which should have told me to avoid that auction. Well, the crank was bent. It took me a few hours to straighten it and now I have a nice engine that cost a few dollars, but it could have been a total write-off.

Buy smart!

Jack