I think you may end up spending a lot of time gaming on Mistplay to earn $100 on Mistplay. I imagine Mistplay may pay more when more users ask for higher earnings, or there are other pay to game websites and apps which pay more cash for playing games.
It sounds like those ads where "average" people can win big by playing slot machines or poker and they even feature people receiving checks in the ads. I don't think they're worth the time. I imagine you'd have to sink a lot of time before you see any returns.
I feel Mistplay could be worth it in countries where the cost of housing/rent, services like cell phone service, and most items like food is more affordable.