[theweatherman]

the answer is entirely read dependent. The continuation bet is not as prevelent as you make it seem. Rarely do I find a consistent continuation bettor. With this in mind you want to challange every Continuation bet they throw at you.

However your not going to be able to know which is a c bet and which is a value raise without wathcing the player and understanding his level of play.

It also has a lot to do with position and how many other players are in the pot. Not to mention pot size. Contesting every 2 dollar pot with raises and c/r is not a good idea.