In my experience, psychology students tend to be insufferable know-it-alls that think because they got a first in their abnormal psychology module they can go around diagnosing everyone they meet with random rare psychological disorders.
They also act like their degree is exceptionally difficult, when they actually are on the lower end of contact hours, and their course is of only comparatively moderate difficulty.
It's also somewhat like the "media studies" of private school students, i.e. the subject the upper middle class WASPs take if they were too lazy/stupid to get decent grades in e.g. sciences, languages, maths, etc.
Of course this is very biased and entirely anecdotal :P