Bought one pin unseen from a local Pinsider who had already sold me two other machines (with which I'm very happy and had already looked over and played prior to sale). He knew I was looking for a Medusa and said he had found and restored one that is even nicer than the other two pins he sold me (and boy was he right about that!).
At this point I'd take his word on pinball, or anything else, at face value but that kind of trust takes a while to build.
Got my Fireball shipped to me from out of state based on pictures alone. Has a couple minor issues, but all of them were documented in pictures (though I did not notice some of them until looking at the actual machine and then going back to look at the pictures again). Would probably still have bought it if I hade seen it first in person, but not at the price I paid unseen. Also annoyed that the seller broke off contact (though previously responsive to PMs, texts, and emails) immediately after the pin arrived and I signed off on the delivery form.
At this point I would not buy unseen again unless from someone I know and trust or a reputable seller with an actual store/business like Cointaker, GAP, Hemispheres, HEP, HemiOrange, etc.