The next personality McCutcheon covers is NERVOUS/SHY/SUBMISSIVE. This is different from introverted. The nervous/shy/submissive character has nervous ticks like fidgeting, trembling, clenched jaws, blushing, or stuttering. They are apologetic, deferential, won't make eye contact, and solicitous. If your protagonist suffers from this personality trait, you'll need to find a way to make him sympathetic so the reader won't walk away. I once began a book where the protagonist became morbidly obese, and everyone (including his parents) mocked him for it. I put the book aside and never finished it because I felt too uncomfortable to identify with the hero. If you decide to use this personality trait for your hero, he definitely has a flaw to overcome. If the final conflict of the story is a confrontation, then your hero has a lot of preparation and growth to experience before the book's end.
SAD SACK/GLOOMY GUS is the next type. This person mopes around, slouches, sighs a lot, complains, has a "poor me" attitude, never seems happy, and generally drags everyone around him into a funk almost as deep as his own. Be ultra-careful with this character! In real life, people like this are hard to put up with. I know one of these people, and I avoid her like the herpes virus. This character is not only unsympathetic, she's down-right toxic. Eeyore from Winnie the Pooh might suffer from a bit of this, but he's sympathetic because he genuinely cares for his friends and will do anything to be helpful, even while he's grumbling. If you use this character trait, couple it with positive traits to balance her negativity, or she'll be nasty.
(This image courtesy of wikipedia)
The next two personality traits are INTELLIGENT and IGNORANT. I'm pairing them because they both have the same danger: they can lead to stereotypical characters. The brainy nerd who wears glasses and is socially awkward. The ditzy blond who couldn't find her way out of a paper bag with a map and a flashlight. The bumbling, naive country boy who's built like a John Deere tractor but can't spell CAT if you give him the C and the A (I stole that one out of a Robert P. Parker book). Intelligence or lack thereof can be an important part of your character, but avoid the stereotypes. To do that, pair the intelligence or ignorance with other traits that you don't expect to find together. Bumbling but loves sports. Intelligent with a secret belief in UFOs or astrology. Bookish, but loves punk music concerts. The more variety you add, the better the character and the further away you get from stereotypes.
I'm also listing BORING and ECCENTRIC together for the same reasons above. A boring personality talks a lot about himself or about other mind-numbing subjects, has poor listening skills, might be prone to babbling, speaks in monotone (remember that teacher from Ferris Bueller played by Ben Stein?), never changes his routine, and is afraid of change. On the flip side, the eccentric is weird, original/individualistic, doesn't care what others think, could be mad/insane/deranged, enjoys excess and extravagance, and may enjoy shocking people with unconventional behavior. These characters make great comic relief in secondary characters because of their uniqueness. If used for the protagonist (or antagonist), pair these traits up with something more normal/likable like a devotion to pets, exceptional generosity with money/time, or immense compassion.
I'll stop here. Did you find anything interesting to use? Can you come up with examples from books you've read where the author took one of these toxic personalities and created a fabulous character?