[andyfox]

Brier and Ciaffone state in the book that they don't necessairly endorse the previous action; they are only assessing what to do given the action as it was.

I don't see how the 8 makes two pair more likely. If the blind had one pair and bet the turn, why would he not bet the river if it gave hiim two pair? I suppose the button could have J-9(s) and have made a straight but in 30-60 it's not unusual for him to have raised the flop with this.

And I'm not so sure a cluttered board makes two pair more likely. I think a board with an ace on or two face cards does.

To me, this points up the problems of limping. Now come the river you have a player behind you. I worry more about a cluttered field of opponents than a cluttered board.