It's pretty complicated. You need to look at their track record, maybe who is behind the company, look at reviews on the internet and if they are or aren't regulated by some entity. If you're looking at casinos you might want to check if they have a license, but in the crypto space I haven't seen many casinos with one.
Casinos are hard to verify for authenticity. Most likely, for this type of service you need to check how long the site is working, who is the owner, watch reviews, to check is it a global one (how many users and which partners it has)
I also did not see a license of crypto casinos, I dont even know where It could be registered