I see no reason as to why should I not trust the casino I'm playing on. There are tons of gambling sites out there that has earned the trust of the players because they have been there for a while now. For example, primedice and BustaBit. People might claim that the website is rigged or something but they are just saying that because they were unlucky.
Yes, reliable sites can be trusted, they don't cheat or scam. They earn rake of bets, and margins of sports betting. They earn a lot if the customer are a lot. No need to cheat, for long term and real business.