No guilt. No tip. Never. If they want more than the listed price they should raise the listed price. Social customs/expectations/guilt/whatever be damned. I never tip. Never have, never will.
If you go into the situation intending from the beginning not to follow this convention but receiving the benefits of it, then you are not acting in good faith. You are, through nonverbal communication, misleading the waiter.
Consent should matter when two parties enter into a transaction, and it should be informed consent. If you think what you're doing right now meets that standard, then next time try telling the waiter at the beginning that there will be no tip, and see if it makes a difference.