That's a fair point. I wouldn't expect him to bet against two drawing hands, but against one drawing hand and one presumed made hand, I would expect a bet. You're right that we can't give a bet 100% probability on this river, but I think it's still pretty high. Chufty is between 3:1 and 4:1 to make his draw, in which case he still mightn't raise (fright of DO already being ahead combined with wanting to get an overcall from me), and I am probably calling all the time when chufty folds.