Well, if your playing Texas Hold'em, and you are playing heads up, the odds are as follows:
A,A off suit vs K,10 off suit: There is about a 85% chance the Aces will win.
If the flop comes A,Q,J (no flush possibility) The odds are only 64% in favor of the K,10 off suit. Even with the K,10 making a straight after the flop..
Remember, there are two cards left. If the board pairs, the Aces win. So if any two of the same cards come on the turn and flop, or any one of the remaining 3 Queens, 3 Jacks or the remaining Ace show up, the Aces win.
That is very true. It is much more difficult for people to team up in casino games. The floor managers and dealers (and also the players) can easily (most of the time...) spot people playing as a team.