What really really irks me are bad/incomplete scans of Public Domain works being sold for 99 cents or some similar low price on Amazon & the like and it's impossible to tell what the edition is because the reviews all appear to be for the audiobook.
I'd gladly pay more to avoid that. I had to buy some Kierkegaard twice ... again it is the incomplete/asymmetrical information problem. Also there was some issue of Wikipedia articles being compiled and sold as e-books under the subject author's name, wasn't there?