Too persuasive is the moment you try to force a decision.
Are you trying to push your product? Yourself? Your company? Can you feel when doing so that your audience is unhappy and often gives you a “leave us a brochure” or, even worse, “what rebate can you offer?”, or the beloved “we will call you back”.
Being only rational makes you become too persuasive as you try to push elements that the decision maker can’t grasp.