[MathEconomist]

Money already in the pot is part of what you can win by calling a bet, so it is correct to consider money already in when calculating pot odds. But your current call is not part of what you can win, so that should not be added to the pot. When doing an after the fact calculation and asking what was I getting, you need to only consider the money the other guy puts into the pot after the decision point.

As far as not giving implied odds, I should emphasize this is against players I don't have a good read on (though it's good to always keep this in mind). So say I make a pot sized bet on the flop against what I assume is a flush draw, and that 3rd suited card hits on the turn. In order to be correct in calling that bet, the other guy needs to get in total about 4.5-1 on his money. He already got 2-1 from the pot, so between the turn and river I don't really want to put in another 2.5 times the original pot. So if he makes a pot sized bet on the turn (3 times the original pot) I would generally just fold. If he makes a smaller bet, but I think I'll have to call again on the river I can fold. But if he checks the turn and bets half the pot on the river I can call.

This gets varied a lot depending on the situation and what reads I have. But in general, you shouldn't be willing to pay off enough on later streets that your opponents were correct to call your bets based on the implied odds. Note that this is actually a specific application of the general principle that how you play early streets should be influenced by how much you're willing to pay off on later streets unimproved.