Just about anything Hobbycraft Canada made up to about a decade or so ago could be hell.
Their current stuff isn't bad since they cleaned up their act from the old days.
Two kits that come to mind were both from them. A 1/72 FW-190A, I don't know what its origins were, but it was terrible nose to tail. It was the only kit I was so unhappy with that I actually wrote a letter to the manufacturer and gave them hell for even thinking to put it out there. The fit was barely there, the panel lines were suspect and the decals looked like a high school shop class's silk screening experiment gone wrong.
The kit that really put me off of Hobbycraft for a long time was their 1/72 S2F Tracker. I later found out it was pirated from the Hasegawa kit. Oddly enough, the decals were the only good thing about this kit. There was poor fit all around, hazy clear parts. I don't know what sort of plastic they used, but it melted down like nothing I'd ever seen before and I wasn't using anything fancier than Testor liquid cement.
Other dishonorable mentions I can recall:
Aoshima's 1/72 Hawker Hurricane
Airfix's 1/72 Boulton Paul Defiant
Hasegawa's 1/72 EE Lightning F.6
Monogram's 1/72 Panavia Tornado
Revell's Visible Woman (great idea, poor engineering)
Even the best companies can release a dog of a kit that just leaves you shaking your head wondering what they were thinking when they engineered it.