Thankfully, conventional online casinos are inspected by various serious amateur staticians and consumer groups. There's a number who have superb records for honesty and integrity, and offer games like blackjack and video poker which play exactly as their real world counterparts using true random numbers. Of course there are some sleazeballs, but you can find them out easily.
I wish there was such for SL casinos; who is to say that a casino's machine isn't rigged? It is amusing to look at the vendors of such machines on SLExchange and see them advertise their machines being rigged (and thus giving the player hints as to what machines to avoid.)