Coming from a sales and promotions standpoint, I'd say it is the other way round. If you don't believe you are good, it may be difficult to convince others. Of course, there are people who make compleat asses of themselves because of what they believe themselves to be. But, deep down, I think a person who is really good at something will know it and that is what should give them the courage to call themselves a "good" writer, picker or whatever, even before others may say it.

Just another viewpoint, not one I necessarily follow or believe all of the time.

kat