Thank you for your comment.

Definitely many men will see, "I'm just not interested," as you not having given them a fair chance to demonstrate how great they are. I wish I could offer advice on how to make your assertions more impactful in the mind of the man harrassing you, but unfortunately, the problems are with how he is socialized, and don't know if there's any one approach that's going to untangle that in the context of one interaction.