Some faces don't have a lot of symmetry. This man, sketched from a mugshot had very interesting ears. (I think the eye condition was congenital. The photo didn't look like he'd recently had a beating.)
Our society spends a lot of time worshipping symmetry and maintains certain "standards" of beauty, such as impossibly large eyes, painfully thin women, and a rather odd puppy-dog expression on most young male models or actors.
I find imperfections a lot more interesting to observe and sketch.