It's really tough to just go by the ToS. Some books say that they may require a 5x if they suspect using a mixer. The book may never use that clause, but it's still there. They also don't have to prove mixer use, they can just say they suspect it. If they actually require a 5x that something that could be acknowledged in a review.
That's a good example. If that point is there, the casino has the right to take advantage of it. Whether they will use said right is their discretion. It's certainly something I would consider unfair. And if you think about it, any use of a casino with crypto can be considered mixing your coins. You deposit your coins, which go into a big pool with those of other players and when you request a withdrawal, you get back something completely different with a different history behind it. You mixed your coins.
The same goes for confiscation of dormant accounts. The clause is there but may never be used.
I have noticed that with certain casinos while doing my checks for my Withdrawal Fees thread. My dummy accounts created only for that purpose suddenly stopped working in some instances. That means they deleted it from their systems after x amount of months without real use. It's not a problem, as long as they don't confiscate your deposits or winnings with it.
But online casinos also have dormant account fees. That's something that could be considered unfair. At least, it's in the grey area.