Those suspicious things will depend on the casino, although we do not try to do any suspicious things that can make our account on their watch list.
The shady casino will use many ways to trick their members because their purpose is to freeze the account so they can possess their funds without having the intention to refund the balance.
It already happens to some people and even if they complain to the site, the site will easily ignore them.
So only research will help us avoid this thing so we can play gambling without worry.
Casino is centralized party, all you need is picking the reputable casinos first since you need to trust the casino with your money. Same like when you invest in new project or lend your coins, you need to trust the project/sites and understand what's the risk behind it.
If you choose shady casino e.g. 1xbit you have no hope when something bad happen to you. Even they're online and active everyday, they will not resolve your problems. So never play in shady casino and choose the reputable ones.
We can actually see good risks in this forum, here we have a lot of good or bad judgments about offline sites or casinos and I quite agree with what you say because at least we are in a casino that really has a good reputation of course we can be more secure and comfortable because they have been tested.
As for the risk, I think it goes back to what we did there because sometimes there are still many people who don't really understand the risks and the rules but jump right in so they feel cheated when something doesn't go the way they want.