While there are reviewers that just leave their links in hope of referrals, the two I mentioned above have spent their own money and are more direct when it comes to which casinos are good and bad.
I don't want to say the name of anyone here but all the reviewers are also biased in many ways. For example, in any casino review site, if they rank casinos, they will list the one at the top which provides them the most referral commission. I have seen that almost in every casino review site. Isn't it a biased opinion? Well, I'm aware of both the sites you mentioned and I have to agree that they are quite good in terms of reviewing a casino and helping someone pick the best casino.