Originally Posted by 2bet

I can only speak for our site, but bottom line, Only play on sites that allow 1 ip per player, or, you will sit down at a 10 person table, and 9 of the players will be 1 person. We only allow 1 ip per player, and monitor it daily. If you try and log on multiple players under 1 ip, both accounts will get banned.

Of course there are ways around this, but it takes a more skill person to get around it, thus for increasing your chance at fair, real play dramatically. In addition, sites that have alot of amateur players is more recommended then some of the sites that endorse professionals at their tables, like the ones you have mentioned.