It's stark in the arts, but it applies to almost every human endeavor. As an example in the arts, I dance, and I'm good at it according to almost everyone who sees me dance. But I see myself as a terrible dancer. If I make a video of me dancing, others see every part that's well executed. I'm accustomed to them, and I tend to ignore those parts in favor of every part that's sloppy, every part that just doesn't look right.

And it's no different for code. You know what one of the marks for good code is? If the guy writing it is tearing it apart in the comments. Where do you see /* This is a dirty hack I'm ashamed of */? Usually right next to stuff that's a stroke of genius, or at the very least really good code.

It's strange that the more you know about something, the less comfortable you get with your knowledge, but it seems almost universal that "Ignorance is bliss", or rather the corollary "The more you know, the less you think you know".