I bought a bunch of waaaaaaay overgraded common date walking liberty halves when I first started getting back into collecting about 1996 or so. Paid a dealer locally over $15 each for them, which at the time was like paying about $40 each for them now. When I did the homework I found that I didn't have what I thought I did. But I also learned that reasearch was what I needed to do so that I didn't buy foolishly in the future. Needless to say, I never bought anything from him again. A few months ago I sold them for melt...
Not too recently I purchased a 1893 Columbus commem. half-dollar. Detail-wise, it's probably around MS-62, but it was def. cleaned upon taking it home. I don't know how I missed the lack of luster at the store. Needless to say, I've had a few not-so-great coin buys from this place near downtown Denver, but I don't think I'll be going back anymore. Only paid $20 for it, but still, I don't think it's worth that.
An 1858 Flying Eagle that was cleaned, net VFish - I overpaid by about $50. At the time, I was just getting into the hobby and had no idea that cleaning could cut a coin's value by 50% or more. As I found out from another local collector, the dealer I purchased the 1858 from rips off new collectors in order to make a living.
1652 Pine Tree Shilling + eBay = friggin' disaster. I paid $350 for a piece of pewter. Thankfully, the guy was selling it as genuine and, after a lengthy ebay dispute, I got full money back. NEVER AGAIN!
