This doesn't talk about Social Anxiety (only mentions it as a potential disorder that perfectionists can suffer from), but I found it pretty interesting, and hit home for me in a lot of ways. Perhaps striving for perfection is one thing that could be at the heart of things like SA, OCD, AvPD, etc. Or it could be the opposite- a defense mechanism after you've already developed anxiety/depression. Thoughts?
http://www.ucdenver.edu/life/services/counseling-center/Documents/The-Perfectionists-Script-for-Self-Defeat.pdf
http://www.ucdenver.edu/life/services/counseling-center/Documents/The-Perfectionists-Script-for-Self-Defeat.pdf