In the past I have argued not so much against the rule, but the notion that there was no other reason to check the nuts on the river other than collusion. I've pointed out that there have not only been times when I have checked with what I was sure was the best hand (not the nuts) in order to see what my opponent was playing with, but also times that I have paid off bets on the river in order to gain the same information. So to me, the concept of someone checking the nuts on the river in order to gain information on their opponent is not so far fetched.
Recently I played a hand, after which I had to wonder about this particular rule. I had raised 4x pre w/A-Q suited from the button with one limper in front of me. The blinds fold. The limper calls my raise and we see the flop heads up. The flop comes something like 2-9-10 with two clubs. The other guy bets half the pot. I call with the nut flush draw. An Ace hits on the turn, giving me top pair. My opponent checks, and I check behind, leaving him the opportunity to
bluff at the river. I should probably mention that I had been cleaning my gun as I played. So I was a little distracted when the 8 of clubs landed on the river, but not so distracted that I didn't realize that I had rivered the nut flush. The other guy makes a half pot bet. I called, knowing that my nut flush was good. The other guy turns over 10-4 of clubs.
So I had taken down a decent pot and gone back to cleaning my gun when it hit me that I had probably left some money on the table. I was supposed to raise his river bet. Before seeing his hand, I should have recognized the possibility of him having an Ace, a straight, or a lesser flush that he would have likely paid me off with. After seeing his cards I further realize that he might have put me on just a pair of Aces, or a straight, and not only paid me off, but possibly have gone all-in over the top of me. And even if he folded, I wouldn't have lost anything by trying to extract a few more chips out of him.
So there I was sitting there kicking myself in the ass, angry because I might not have gotten maximum value out of my hand when something else occurred to me. If I had been playing live, I would have been penalized for not raising with nuts. I didn't know this guy. I wasn't soft playing him to be merciful. I wasn't even looking for information. I already had a pretty good read on how this guy played. I just brain farted. There was nothing sinister going on. I didn't have any ulterior motives. I just wasn't playing full attention. Granted, in a live game I wouldn't be sitting at the table cleaning firearms. But the point is that people get distracted or just plain make mistakes.
Of course we can't rule out the possibility of two players knowing each other, and in the case of them being in a hand against each other and the one that is last to act in that hand having the absolute nuts, that they might decide to soft play one another. But should that scenario always be assumed to be the case and any other possibility, such as one player trying to get read on the other, be disregarded?
