[rory]

Call and put a note that he donks when he hits his ace on the river rather than risking it getting checked through and keep on playing. You absolutely can't fold without a note, so call and now make a note and keep on rolling. The call is right EV wise vs. an unknown and you get a very very valuable piece of information vs. an opponent to put in his note. I'd never fold with no note. I'd call and be really happy and excited about getting to write a detailed, specific note against an opponent in a +EV situation. I'd call the next time he did it too given the same exact situation, knowing it was a slightly less EV situation (a cognizant opponent would be less likely to bluff me because I showed a propensity to call him previously) but a more valuable informational situation (another data point). I'd note if he did it to other people. I'd note if I ever saw him bluffing, even once, when he did it. I keep a counter at donking-at-river-scare-cards, so I can try to get an idea at the frequency of bluffing, even if it is a really rough estimate because a really rough estimate is a lot better than no estimate. And seeing him bluff once is a lot different than never seeing him bluff. I dunno. Did I get off track? I did. Call. Write the note. Look forward to expanding on it and hope that this one note leads to another note. Which leads to another note. Which leads to a trend. Which leads to an identification of an exploitable weakness which leads to some ridiculous river bet-fold or bluff raise or something that you can't even post here because it is in your note so you don't bother and you wind up with a higher BB/100. But you have to make the +EV call to see his cards to get the information to start the whole process. Don't try to save bets vs. unknowns when you are also robbing yourself of the information you need to make the unknowns knowns. Pay and then make them pay.