It is possible that most of those accusations against those casinos is true, even if all is not true, majority of it is true. Some non reputable casinos might have indeed scammed those guys that create the scam accusation topics while some of those accusations are also a false accusations which was the fault of the gambler and not the casino mentioned. If any reputable casino on this community is falsely accused, they will definitely respond to clear their name or their representative will likely respond.
Some of those accusation reports are true while some were not due to the reason being that the gamblers are the ones at fault from their end, we can also get some trusted ones from the scam accusations and discussion thread on that particular gambling platform, to cap it all, we may also go through tje reviews left on those gambling sites in other to have an idea on their reputation before using them.