I used to try to be very stringent in my attempts to find out what companies or organizations supported this or that political or religious cause and avoid those who supported organizations or causes with which I disagreed. This turned out to be a huge time consumer for what I consider very little benefit. Everyone—every major retailer, specifically—supported something I didn’t like.
The reason I say that constantly monitoring companies’ supporting practices is a waste of time is that it’s a never-ending endeavor. If you choose to enter into such an endeavor, you will find that it leads to two major problems. First off, you will never get to the end of your search. Companies and organizations frequently change whom they support and how much goes to them. Secondly, you will find that you’d have to live a monastic life out in the middle of nowhere, stay off the grid so that you don’t pay taxes (the government would quickly be on your boycott list) which means you’d have to quit your job, and live off nothing but the land—land that you couldn’t own lest you end up paying taxes on it.
Therefore, I no longer pay much attention to who supports what. Here’s a blog post that someone sent to me that expresses my feelings on this. I’m not Catholic by any means, so I don’t agree with the posters Catholic leanings, but her opinion on this topic is close to spot on with mine. (The post is rated PG, by the way).