The only red cards i gotten so far been double yellows or the oh so anoying "lets slide from the side" and the player on the ball makes a insane quick turn so it becomes a tackle from behind. But even those seem to get more yellows then red for me.
Im also loving the new tackle system. Not every tackle means the players goes down the ground.
The one thing I'll give Konami is that the referees in PES6 are pretty much as good as they're going to get (one can't help but get the feeling that they'll be completely fucked up in the next version though, Konami-styleé).
I think the only thing they can add to them now is decisions based on their line of sight (and the same with linesmen); in other words, if someone's standing in-front of the referee when a tackle from behind takes place, and the linesman doesn't have a good view either, then a foul won't be given.
My biggest gripe with the refs is the way they're used as an additional means of adding "challenge" to the game by having a clear bias in favour of the cpu team. Particularly annoying is when you're winning and the cpu decides to go into god mode and simultaneously, makes the ref effectively sign up for the cpu team (as well as changing the laws of physcis to ensure that every deflection goes straight to a cpu player's foot). The cpu team can now scythe you down and it's not even a free-kick, yet the ref starts blowing for fouls against you simply when you've gone quite close to a cpu player. Subtle it is not.
Also, wtf is going on when you're 1-on-1 with the keeper? I've lost count of the number of times the cpu keeper has come flying out and assaulted my attacker and got nowhere near the ball - clear red card and penalty, but nothing's given. Even the replays don't disguise the blatant foul play.
Konami just can't seem to help themselves...they always have to put some really appauling crap into all their games.
I think that some of you guys who recently has experienced many red cards, have encountered Kazuki Ito. He gives a million cards for nothing, and is - by far - the most harsh referee in PES6. Two of my mates had 3 players sent offeach!.
Lastly, it think it's great, that the ref's are different. That makes it more fun to use the "random-setting", 'cause you'll never know how that particular ref acts.