I think that most Sportsbooks that you can find being advertised on Bitcointalk by users without red trust are legit, no-scam Sportsbooks. But that does not mean that the bookmaker behind it all is not trying to take you for all you got. Even if it means being "unfair" or shady. But in most cases they at the very least follow the laws and regulations. So that is one thing you can be more or less certain about.

Scams are not the majority but rather a minority of gambling platforms. But you should always be careful and check in with the gambling community. Like the one on this forum, for example.

So you are doing everything right, to avoid scams, I would say.