This is why it could be good to test them with little money first, that's if the bonus offered is so important to the person. If not, I would advise anyone to go for the old and reliable ones that one could review well online and have rest of mind with.
Another thing is the KYC, I simply can't deal with the casino which is no KYC, it automatically means they are not regulated.
I played with casinos that doesn't ask (from what I know) for KYC before they were doing lots of promotions here and are managed by reputable managers, if they aren't, I won't play there. These casinos though, are now asking for KYCs for some of their users. They were also launched their casinos around that time. Personally , I would only trust new casinos if I think that they have good professionalism and engagement with the community, which is rare to see nowadays since lots of potentially scam casinos are being launched from time to time.