1. writing without a plan for the project
2. writing without clear purpose
3. writing without structure
4. not understanding the reader's needs and interests
5. not taking the position of the reader
6. not using effective layout
7. using poor grammar
8. missing spelling, punctuation or usage mistakes
9. not repeating and reinforcing main ideas
10. not editing for unneeded verbiage
    

 Well, you're not alone! 

Most people just don't know what to avoid or they don't take the time to fix these simple problems.  They have great ideas and persuasive arguments that never get to the reader because 'noisy' errors get in the way.