Please no flame wars because we all know every manufacture has made something we wished we never bought.
I had two not one of the worst engines I ever bought and they were:
Two Williams brass Hudson's, the regular Black hudson and the Dreyfus in around 1990 for the blowout price of $299.00 each. They looked ok but boy where they lousy runners and I am being kind. No matter what I did I never got them to run smooth.
I was dazzled because I always wanted scale 3 rail locomotives and they were on blowout. Lesson learned.