Yes in general if you gamble only on the reputable bitcoin sites listed in the various threads on bitcointalk you are usually safe. Because if one user gets scammed, he usually is the first to open a complaint on the forum and others will investigate the issue and the site might lose gamblers.

However the problem is most people don't use bitcointalk. One reason is that its only English based and there are hundreds of languages around the world. Another reason is that its too much reading. So most people just google "bitcoin gambling sites" and go to those top 10 lists with affiliate links and gamble there. However those casinos aren't properly vetted and might be scams like they were in the past.