Ok, so I've personally seen a few ugly cabs in my day, but this one takes the cake:
http://cgi.ebay.com/METAL-SLUG-4-NEO...item563bc99924
What an ugly piece of shit. Obviously homemade. Oh and how 'bout this one?
http://wickedretarded.com/~crapmame/5.html
Anyway, feel free to post pics of poorly constructed arcade cabinets so we may laugh at them.