A lot depends on the opponent, the board texture, the prior action on each street. For example a river bet or 3-bet on a board that you were the aggressor on and they just called along that appears to be a missed flush draw...I'm calling or even raising a good percentage of the time. Especially if they flatted my raise preflop. Sure sometimes it's a set or two pair so I'm cautious with just a pair, but def calling if not raising them if I have 2 pair or better on boards that look like obvious draws with a calling along opponent.