Is there any way to determine if an online games site is on the up and up?

worldwinner doesnt charge you anything to be a member. its free then you can upgrade for a one time fee of $10 plus they give you $10 game credits plus the $10 you upgraded with. check them out and if you like the games then upgrade. when you upgrade you can challenge other people. i’ve been a member going on 2 years now.