Interesting, and maybe a bit ironic, considering that Dowling was the one that coined the phrase 'Buy the seller'...
Quite honestly, it's not too surprising; there have been a number of 'above board' sellers and dealers that have dipped their toes into the questionable and shady at some point or another. If there's money to be made, the risk will always be there. Ultimately, the onus is on the buyer to know exactly what to look for, to do the research and to know what's good and bad before parting ways with their money. It's not any excuse for unscrupulous activities, but the best way to protect yourself is to be informed. There is plenty of information out there on the Internet, and oddly enough, some of the best informational resources are rep forums. Go figure...