Scum Dumb

A person who is scum and who believes themselves to be scum smart, but in reality they are so stupid they would try and claim for disability benefit and home help from someone they work out with at the Gym

They are definitely scum dumb as they tried to make an insurance claim for new carpet claiming it was damaged by Penguin that flew in through the window

Scum Or Dumb

When someone has done something atrocious due to negligence, they are either scum or they are dumb. They either knew what they were doing wasn’t right, and did it anyway, or they were too dumb to know what they were doing.

Guy1: You hear about the cop that killed that kid, thinking the kids corn dog was a machine gun?
Guy2: Are you going with scum Or Dumb here?