If you favor legalization for a good reason, why should you care if others use bad logic to also favor legalization? Simple. Their support makes your arguments seem less valid. This is not fair because you probably have some good points. But, this is the cost of a bad argument.
As I dislike bad logic, I was elated to find the following exchange in the comments on a popular marijuana article from Digg:
Stop throwing innocent people in jail because they have a plant on them. Most people that don't smoke don't realize how serious an issue it is, people are literally being sent to jail and prison because they have a PLANT on them! Imagine you were arrested because they made cotton illegal and you were wearing a T-shirt? [NightC]Silly, right? Here's my favorite response:
Look, I'm all for legalizing pot, but please stop trying to support it by posting your reasoning, and I use the term loosely, because horribly simplified arguments like that are not helping. [egoideal]I could not agree more. If you have a good point, why ruin it by adding a bad argument into the mix? Yet, that's what the pro-legalization camp looks like: For every 10 arguments, there are only one or two good ones. Someone who might be persuaded by a good argument won't listen to your good points if you also throw senseless garbage at him.
Of course, if all you have are bad arguments, your best strategy is to spray them anywhere and everywhere. Maybe someone will believe you if only you contact enough people. As of right now, I'm just a casual observer, waiting to be convinced.