This could backfire badly -- VISA could just decide to forgo the revenue it gets from processing all porn related transactions for reason that some is unlawful content.

The "Final Solution" for both lawful and unlawful Internet porn abatement.

Be careful what you ask for you may just get it.

There are other more specific ways to deal with the problem.

Reporting such matters to payment processors is a good idea as they have acceptable use policies that preserve their relationships with the credit card associations' member banks or their status as member bank sponsored parties.

Dealing directly with the Credit Card Associations could jeopardize lawful porn transactions as well -- not a good idea at all.