shitstain

A dispicable crungy person who seldom washes, rarely wears clean clothing, brushes his teeth, or gargles. His hair will generally be greasy, poorly combed, and encrusted with dander. His breath will be toxic, and he will only wash his hands after using the restroom if he is in the presence of others.
He is arguementative, arrogant, and believes himself to be a genius, although he rarely exercises good judgement in any matter.

Boy, that guy in the convertible is a real shitstain.