I think I came across a casino that was posting biggest wins in their casino on their Twitter account, but they never gave details. They only posted that $ amount was on in sports betting, but never showed ticket, event used for that prediction, nothing. I think that is red flag, when casinos fake or hide information about winnings in their casino.
Or casinos that add their logo over video that has nothing to do about gambling, and add promotional info in post. Video like this
https://x.com/bcgame/status/1871024774413218142?t=v56Ie0r6_wSBDEc6tJyVkA&s=19. Woman earned/made "6 hundred and 85 dollars" (she does not state how and where), but in post it is tried to show that she has won 60,085 in gambling.
Those casinos that also hire influencers who showcase fake wins. These influencers will promote these casinos by claiming how they had easily won thousands without stress. They will never give clarifications on how they won, but keep showing big wins. This is indeed a red flag since they are deceiving people.
To sum-up that, if your experience with casino starts with a lie, dont expect anything good from it.
Today it is best to check everything you see online or what others say online. Even if what casino say and show is true, we are so used to being deceived, that it is worth to spend some time and check everything. I know that not everyone do that, but new or never seen before game provider can be a red flag as well.