Usually opponents don't play sets strongly on the flop. However some do if they feel you are over-aggro on your betting. I feel your response should depend on the size of the raise versus your stack sizing. At a certain point if your hole cards aren't improving much moving forward, especially versus sets on a dry board, so you have to fold. It is very situation-specific.. but know that on a dry board you are drawing dead at about 2-7% versus a set.