Some ugly aeroplanes:
Piper Pawnee
PZL M-18A Dromader
PZL 104-35A Wilga
Antonov AN-2
Aviation Traders Carvair
Cessna 337
Fairchild SA-227AC Metro III
Ilyushin Il-76
Antonov AN-124
B-52
F1-11
Britten Norman Trislander
The Shorts Skyvan is even uglier than the Shorts 330/360.
Mind you, I would be very happy to fly any of the above mentioned aircraft if someone were to pay me.....