I just found this:
" 1. Is the casino Provably fair?
Whenever you play at a casino (physical or virtual one) there’s always the option that the house may be cheating. Of course with the more respected casinos this is rarely the case, but if you go to a somewhat unknown Bitcoin casino site, how can you know that you are getting the winning odds you’re supposed to get.
A trustworthy Bitcoin casino will know that their “house edge” is enough to make a profit and therefore will want to prove to their players that they are not manipulating any results. They do this through a mathematical algorithm involving cryptography (https://thebitcoinstrip.com/blog/what-does-provably-fair-mean.html .
Bottom line, a provably fair casino will show you how to check that the results of the game you play are completely random. www.bitstarz.com/provability-explained . If a casino can’t supply this proof or isn’t provably fair I suggest betting with caution.
I just posted a vid on another forum about this. The Wizard of Odds has found that even 'provably fair' casinos can and do cheat.
I guess they assume that players won't actually check the hash every time. They might at first, but it's a pain having to do it and most will stop after a while, assuming that the casino is being honest. After all, if the casino knows that it can be proved that they are cheating, why would they take the risk? But it seems this one did.