There's a degree of bogus with almost every listing. Those who aren't faking ownership are faking traffic or earnings and most of those who are not faking any of that won't admit how much of time the site actually takes to manage / run (i.e. deceit about input costs). Many don't see the difference between marketing their site and ...lying, and the number of things they can lie about is limited only by their ingenuity and imagination. Even if they are not lying at all they could be omitting to tell you that a major inward link is going to be pulled soon. Or that they are under threat of a lawsuit for the domain name infringing someone's trademark. Or that the merchant paying 90% of their earnings is planning on reducing his affiliate commission from 5% to 0.5%. Or a million other things. Buying a site isn't for the fainthearted. Or the risk averse.
In my day job I spread sweetness and light by recognising and rewarding the positive in everyone. :)