who is doing super shady appearing online gambling?

At a guess, mostly people who for various reasons aren't allowed to gamble on more 'legit' sites, either because of their age or other local laws and jurisdictions. If you 'need' to gamble and are forbidden to gamble legally, then you will find a way to gamble illegally. Just look at the 'offline' world, before sports gambling became basically legal, lots of people would place bets with very shady operations.