Even big casinos will certainly have complaints and scam accusations but it will not reduce how trustworthy they depend on how they handle each complaint and for scam accusations will not be meaningful if those who do it not have strong evidence and simply just ignore it.
That is just being part of the casino world. I have seen plenty of weird complaints where the customer was wrong and they still kept insisting that the casino was a scam, and nobody really cared about it. That is the difference, if the casino is actually a scam then everyone will stay away from it, no matter how much money you spend, you will be known as a scam.
There is one place right now in the bitcointalk where we all know they are a scam casino and they are spending so much money on signature campaign to just get people to defend themselves and we all know it will not be enough and we will always call them a scam. That is the difference, we know the right places are right, like duelbits is great, but when a casino is a scam then it is not just one person, it is everyone that calls them a scam and that seems to be the key difference.