The Beech 18, when operated in Canada's north, received the "widow maker" appellation, especially when operated on floats. The aircraft could be over-loaded easily, and could display wicked stall characteristics. Single engine performance was only acceptable when no load was carried. I am not aware of the military giving this aircraft a bad name, however.
As for the previously mentioned Fairey Battle, it should have been named the Fairey "one-sided Battle". Although they gave good service as a bombing and gunnery trainer, a veteran I knew said the glycol fumes he inhaled from the chronic radiator leaks could be nearly incapacitating.