AFAIK there are no tools to see if the website visitors are fake but you can take a look in their alexa rank if is popular or not.
There are hell a lot of SEO services that let you fake your alexa ranks, i would not be surprised if a rouge casino will not be behind using such services.
Also, sometimes there's a gambling site that also faked the bet history to get some attention from the visitors.
Exactly correct, there is no hard and fast rule in getting the correct stats other than using your conscience while placing the bet, it is your money and you know it better, that should be the mindset.