I recommend you to read reviews and check the casino's licensing to ensure it's legit and not a scam.
Review sites is not much reliable since their are made up reviews online and even those scam casino is well rated that's its dangerous to follow them then gamble since they recommend those casinos to you. Also licensing doesn't guarantee that a casino is legit since there are series of incident happened where license casino turn into scam so don't trust much on a casino if they have this documents.
So far this site is somehow reliable to me
https://www.btcgosu.com/ in terms of reviewing those casinos, but people still should do other more research so that they could able to verify if the sentiments of real people is the same with what those review site written. We have bitcointalk to verify everything since feedbacks of people here are more reliable than those other site which the rating they give depends of the amount paid by those casinos to them.
I agree with you that positive reviews or high ratings do not guarantee that the site will be completely safe, because they usually easily pay many people or use bots and so on so that their site has positive reviews and high ratings. In this day and age of technology it is very easy to manipulate things to make them look good when in fact they are not at all. The easiest way might be to ask a friend or someone we know directly whether they have ever played on that site or not, or ask them to recommend which site is trusted.
someone on this forum should be able to easily see which sites are truly safe. We always provide honest reviews here without anything being added or taken away. In fact, here we will share information if there are new suspicious sites and we will share suggestions for taking the right steps.