Went a bit crazy on Twitter during SFN 16. Categorized them on long airport wait on way back.
Check them out: sfn16_tweets_collection.pdf

Short answer: The presenter does not think about what the audience needs to hear to understand him/her. Unfortunately this is an extremely difficult skill to master - requiring one to step into the shoes of someone in the audience. But that's not even the main problem.....

We have all been there. Excited to hear the famous keynote speaker at the annual meeting of the Society for Head-Honchos, you put on your hotel alarm-clock at 5:30 AM (after spending an hour figuring out its cryptic inner workings, designed by a sadistic clockmaker). Barely awake, you stumble groggily into the gigantic dimly lit hall with elaborate chandeliers and musty carpets. After looking around stealthily to see if you know anyone (you don’t) you settle down with your coffee and fish out your notepad (that you will never see after the meeting) and the fancy pen (that you stole from the hotel front desk but will lose promptly). At least the talk will be worth it, you think. It’s not....

An old but excellent Powerpoint by Rita Balice-Gordon who was at Penn (this was available online for a while so hopefully OK to share, I've added some of my own notes over the years...):
Link to Presentation

This is how all of our insights come about...

Story of the Roy lab (probably not unusual). What starts as a small cute paper eventually bludgeons into a behemoth that can probably be split into two or more papers, but its not.....hardly the best strategy, but scientifically satisfying.

....generated some good discussion on publication practices
http://biorxiv.org/content/early/2015/07/11/022368

It is astonishing how many scientists - even well-established ones - don't know how to write. The only book one needs to read is "on writing well" by William Zinsser. What's the excuse?

My takes from this book, relevant to scientists:
1. Writing is a craft, and like any craft it can be learned.
2. Good writing = good thinking. Muddled brains write muddled sentences.
3. There needs to be "joy" while writing. If you feel the drudgery, your reader will too. Usually you will need to force yourself to be joyful. Apparently most good writers do this.
4. In the end all writing is for yourself. Though you want to have a general audience in mind, you cannot write to specifically impress the editor or reviewer (a "rebuttal" may be the only exception). You need to write for yourself.
5. This is the most important thing to realize.....IT'S HARD WORK. Clear sentences are no accident, they are a product of innumerable revisions.