This is a story from when I was just getting started in the Ebay coin business, maybe a year or two in. (In fact, I was still using a scanner rather than camera to get my images--LOW quality solution!)
Here was the original listing from 2006: "Lot of 30 Quality Ancient Uncleaned AE3s." In other words, coins over about 15-17 mm. Nice and round with detail showing.
I even gave some instructions on how to clean coins for beginners (e.g., "soak in distilled water or olive oil," "try using a toothbrush or other soft tool first to remove dirt"). Nothing about using power tools or sand paper or wire scouring pads or anything like that.
Here's the image: not great coins, not terrible, just regular quality AE3s, as advertised. I measured and weighed the coins, which--although I can't remember the exact vital stats--becomes important as the plot develops. They were about 2.5 grams or so, and about 17 mm mostly.
Fair enough, right? There were a bunch of bids, and some guy got it for $29. I sent it down a few zipcodes to him with my thanks and wishing him good luck.
I figured I wouldn't hear much more about that sale except maybe some feedback in a few days.
Oh, was I wrong! To read what happened, check out "How not to clean coins [Part Two]."