I agree to it to a certain extent. When people are not happy or had a bad experience, they are more inclined to write a (negative) review; personally I have done that sometimes. When a site has too many positive reviews, than you know they are fake or were paid to give their opinion. You see something similar on Amazon; some people get paid to review some items and in 95% of the cases, all these reviews are positive to very positive.
Trustpilot reviews don't make any sense to me. If someone wants to see the casino reviews, they have to visit bitcointalk.org and check casino representatives' profiles. If someone has a negative trust, then checking of reference link is enough to have an idea about if casino is a scam or not. There are many casinos with positive trusts left on their profiles, this means that casino is a good and trustworthy.
To be honest, it's hard to determine casino's trustworthiness by only looking at reviews. Many people post a negative review if they lose and don't profit from casino and that's wrong, that doesn't make casino a scam company. If casino pays on time and has no technical problems with good customer support and response time, then they deserve positive reviews but people rarely consider these criterias.