Although this is more relevant to your personal marketing, it helps with product or service marketing. Knowing who you are and who you APPEAR to be to other people is crucial.

Why? Well, because if you are aware of who you are and how you are perceived then you can decide whether it suits your objectives. For instance, you know you are a creative graphic designer, and people who meet you immediately know that about you, then you may be able to pursue those more creative projects. If on the other hand, you THINK you are creative, and come across as set in your ways (you are wearing an outfit more appropriate to 1991, and you are not a hipster), then people won't know what to make of you.

There are people who attempt to seem intelligent by using big words they don't quite know how to use in a sentence. Or people who have to name drop or otherwise show how well-connected they are. These are people who are not aware that other people can see through this.

Or the clueless person...who has no clue at all about how he or she is perceived.

I think that everyone can stand to be more self-aware. Are you getting the same blank look every time you speak? Why? Do people tend to gravitate toward you or shun you? Do you find it easy or hard to make your point? Do people seem to get you?

Are you being perceived the way you are? What can you do to match perceptions with the "real you?"

I am not a psychologist or life coach but  I do think some self-reflection on these matters is important if you want to get ahead in life.