The most thing that makes me crazy about online is delay in withdrawal and kyc requirements, ie failure to verify kyc details when submitted to them and lastly delay delivery of deposit. What I don't really like is after winning and they published your winnings like not secure while dealing online so everyone casino should limit how to publish people's winning.
It is a fact, I also go crazy when I am in a casino and it is not possible that a withdrawal cannot be made, this when it happens for me is already a scam, they may have salvation for possible problems, but I do not consider that it is something what casinos that are new should face, one of the things that casinos with a higher reputation add to me the most, is because it is quite difficult for problems like this to arise, the big casinos do not have those problems, the problems of those casinos there are others that are bigger, but that do not affect withdrawals or directly to a player, they do not give him a hard time.