Don't ever storp writing because you think what you're writing is crap because no matter how bad your writing is, chances are, you'll never have to publicly apologize for how bad your writing is... That is, unless your name is J.D. Shapiro and you wrote the original rough draft for Battlefield Earth.
Battlefield Earth, one of the worst hollywood movies in recent memory won a Razzie for "Worse Movie of the Decade". Shapiro offered an apology for being a part of it's making as well as tried to explain what happened. An Excerpt:
It wasn't as I intended -- promise. No one sets out to make a train wreck. Actually, comparing it to a train wreck isn't really fair to train wrecks, because people actually want to watch those.It's a pretty funny article and gives you some insight on how hollywood works.