Your body and the clothes you wear is an advertising billboard. Agree or disagree?

If you wear a lot of clothing with Logo's on I guess folks could perceive that you endorse the brand but it might be a stretch to say you endorse the brands political positions. I use a number of products and know the company political positions do not align with mine but I still use them (Nike would be one, Apple, another). I choose to wear less visibly branded products as too many have decided to put their politics ahead of their brand.

More important than visible brands is what you wear and what it says about you. With business attire the brand is not visible (normally) but what you wear, how you wear it, how it fits etc. is a piece of it. A well tailored suit or slacks and a sports coat is part of your professional fingerprint. As you are with a company or organization longer, your experience, contribution, ability to get things done etc is more important.

As the old saying goes, first impressions are lasting. People should be more thoughtful about how they appear/dress in public more particularly in the work place.

I totally agree, when service members are out in the civilian population we are a walking billboard for the Military. This is a very true statement.

I agree. That's why I wear a plain blue T shirt and jeans most days. If a company wants me to advertise, they should pay me. There's a few exceptions such as charities I support but not many.