a portion of 'most loose' is the account parameters they have going in.. capital/leverage/quantity/currency pair...
But that's not what you said. They get all those things if they take the other side of the trade or not.
Do you remember Richard Ney? his thesis was that the specialist on the floor of the exchanges and market makers, in their role of maintaining orderly markets, were forced into making money by public investors who entered and exited the market at the wrong times.
I don't, but I'll look him up, thanks. One of my thesis is to look for places where people lose money at a predictable rate rather than where they make money, since it's counterintuitive enough that most people overlook it. I haven't found the golden egg when it comes to a class of investors who is reliably wrong, in my experience they're just random, but I continue to search!
I knew sports bookmakers who let select winning players bet within limits so they could follow along and bet big on those picks, as well as adust their own lone a bit.