Most the time by user experience.
Just play on some big casino or old, you should fine.
Good idea, mate but some competitors use this "SCAM" word + casino name scheme to beat their rivals. Currently, almost all casinos are "SCAMS" as you will definitely find a website, where they are called scams, even decent ones:) When I deal with fiat casinos or even with some crypto ones, I personally look at license (Curacao) and their reputation on Askgamblers or Btalk. I know that casinos tend to pump their reputation by buying reviews, but if you read some 10-30 reviews, you will find some true information about a casino. All in all, gambling is more about fun. Even if you win a decent amount, you will not be able to withdraw it all due to withdrawal limits that you can see in all casinos be it an excellent casino or a notorious scam