[Dagger78]

Effective odds. You must call 2 BB to win the current pot +1BB. You may be getting the odds to call on the turn and then the odds to call on the river but that doesn't make your plan (calling the turn and calling the river) +EV when taken as a whole.

We need to know how often he is bluffing.

Take the example again need 2 pair to win getting 7:1 and 10% chance of a bluff. There will be 9BBs in the pot when you call on the river. So your effective odds are 4.5 - 1.

To make the math easier let's play the same hand 80 times.

8 times he's bluffing and you win 10BB (this includes your call on the river)
10 times you improve to the best hand and win 10BB (this includes your call on the river)

You win 180 bets, and it costs you 160 bets to call the turn and the river all 80 times. So you're plan of calling down UI is worth .25BBs if he's bluffing 10% of the time.

Therefore at 7.5% chance of him bluffing it's break even, anything less than that chance and you're losing money by calling down.

Edit : I just realized we're only getting 6-1 or so on the turn as the poster said we had the odds to call INCLUDING implied odds. Also, I didn't factor in the times our opponent is bluffing and we improved when we didn't have to.