Like most "punishment" effects, the damage returned depends on the damage Geralt receives. Which means that when running a tank build the effect will be minute or if the damage is negated by using Quen, the returned damage will also be 0.
However, the bleeding effect will always work the same unless the enemy is immune.
It is most effective against bruxae and alps, as they may jump on Geralt and drink his blood, in which case they will receive considerable damage.
Geralt will comment that he should have drank Black Blood if such a thing occurs when he is not under the effects of the potion.