Quite frankly, I don’t know why these sites have such a reputation…

While I’m sure sketchy stuff has happened (and things like selling steam accounts is against ToS), most of the more well known sites seem to make money off of sales and limited time products, or direct from developer keys. They buy it on sale, they sell it for more then they paid. Or, they buy it at regular price but then the product is discontinued (like some dbd dlc for example), so they can sell it for more. Or the developer makes the keys and sells them on these sites as a way to get around steams restrictions.

If they were always a front for stolen or fraudulent goods do you really think they wouldn’t have been shut down by now?