Being dressed really well is much more memorable to the client who hired you and other prospective clients than wearing a polo or tee with a logo. It says that you take your image seriously and that you take your work seriously. A logo shirt makes you look like a mall photographer, in other words
cheap. If you really want to make a lasting impression for events, I would get a suit. Nothing with vibrant colors so you don't reflect colored light or stand out too much. I echo the statement that you should see how
@Vtec44 dresses for his shoots and mirror that.
To me, photographing people is often a very personal thing, and wearing a "company" shirt that has a logo turns the photographer into an entity of said company, which to me takes away from the personal connection one might be able to make with their clients. Just my two cents though.