For casinos that are already trusted and legitimate, they will not be afraid of accusations directed at them, especially if the accusations are not proven with authentic evidence, it is the same as the accuser embarrassing himself.
If all accusations have power to damage a bussiness, all companies will be destroyed because no company can satisfy all customers and can not have good relations with all other companies. There are enemies want to destroy your bussiness but only valid accusations have power, legit bussiness will survive through invalid attacks.
After all, people who have been here for a long time and have already enjoyed the casinos who have been accused will cast their vote if what the accusers say is not even true at all. And when that happens, those who are still in doubt will judge who is more worthy of their trust.
Invalid attacks only nurture reputation of legit bussiness more. They don't want to be attacked but they don't worry about invalid attacks which if they handle well, will be like free marketing for them.