The Negative Nancy: Everyone has a Facebook friend that constantly posts about how rotten their lives are. Nothing ever goes right for these people: after complaining about a lousy night's sleep, they whine about their bad hair days, some guy who waited too long at the light after it turned green, and how the vending machine at work is all out of Cheetos. I have other FB friends who have legitimate complaints, like, say, a cancer diagnosis. Don't complain to me about your stupid parking ticket when there are people in this world who are putting positive spins on their chemo treatments.
The Productive Bragger: I have a lot of writer friends on Facebook who like to post how many words in a new story they've churned out in the past 30 minutes. Kudos to you, but how are you getting any writing done, considering you've been on FB updating everyone on your word count every half hour? These people wouldn't be so bad if they didn't post things like "Just wrote a 5000 page story and sent it off for submission! It's been a good morning!" Inwardly I'm cringing in empathy for the submissions manager who has to read that hot mess that you didn't even bother to edit before sending off.