Rambling too much, being too wordy, and not bringing their essays to a concise complete conclusion without wasting paper. nothing more than mental vomit, really. Just kinda BLAAAAAGHED out onto the paper. What is the point of your thesis if you just babble around it?

Hardest thing our AP Composition teacher ever made us do was tell us to write full paragraphs about events in exactly 100 words. We could chug out 4 page essays in 45 minutes...but it took us half an hour to cut a story down to 100 words.

Good lesson she taught us, though. Totally worth the head-to-desk contact.