Just came across this gem, descriptive of YKW*:

snollygoster (noun, slang)

One, especially a politician, who is guided by personal advantage rather than by consistent, respectable principles.

Origin: Perhaps alteration of snallygaster, a mythical beast said to prey on poultry and children; perhaps from Pennsylvania Dutch schnelle geeschter.

* YKW = you know who (in case it's not obvious)