The problem with writing a story is that for the author, the story doesn't occur on the page. It occurs in the author's head. And the story is always good there. I've got some awesome scenes in my mind. I do my best to translate those scenes on the page. When I write a novel, I always think the writing is good because I'm still seeing the scenes in my mind. This is why authors always need to take a break from their manuscripts. The longer, usually the better. After a couple of months, I reread what I've written and I can see all sorts of problems that I then fix.
And then I think it's good . . . until I read it the next time. Apparently the same is true in drawing because this comic says it all.