Review sites just don't impress me much.
Their reviews are not good and truly reflect reputation and quality of those businesses. Other review sites have same inaccurate reviews, trust ratings too. I agree with you that review sites only can be used as additional references but not as main sources to trust or distrust a website.
Bitcasino.io: 2.1 point (Poor) https://www.trustpilot.com/review/bitcasino.io
FortuneJack: 3.3 point (Average) https://www.trustpilot.com/review/fortunejack.com
PlayBetr: 2.4 point (Poor) https://www.trustpilot.com/review/playbetr.com
Freebitco.in: 2.5 point (Poor) https://www.trustpilot.com/review/freebitco.in