I bid on and won a bootleg of the Star Wars Radio Series once. Didn't know it was bootleg, but after the auction ended, I was notified by eBay, that it was a bootleg and that I wasn't required to pay for it and would not be penalized for the action.
It was a few years ago, so things must have gone downhill since then. Sad to see that.
Buyers have more protections on eBay. If you bought the complete series of Gilligan's Island, for example, and it turned out to be a bootleg, you could probably get your money back and leave negative feedback that would affect the seller on eBay.
But, if I were the rights holder of Gilligan's Island, and I knew the set being advertised was a bootleg, reporting the item and the seller would have no consequences.