Green’s Dictionary of Slang

doofless adj.

[dooflus n.]

(US) idiotic, stupid, dull.

Morris War Story 198: Not the doofless types you usually see, but really mean looking motherfuckers [HDAS].
[UK]Mouth mag. 58 (Mar.) 🌐 The cover of the March Mouth shows a completely doofless looking dude grinning a lying grin.