Companies that make product with defects that they know better than to do.
Exhibit A:
Hoover Smartwash carpet cleaner, that we bought from Home Depot a few days ago. (The link is to Amazon, apparently it's gone from Home Depot's site.) Anyway, I was all set to write a glowing review of it because it really did do a terrific job on the carpeting in the family room (day one) and the master bedroom (day two). It's easy to use, clean, etc. and did a better job than Stanley Steemer that cleaned it last time. So all was rosy in carpet-cleaning land, I thought.
Then I read a review on Amazon about it in which the guy complained about the roller bearings on the two brushes rusting because they're made of steel, not stainless steel. Now these are bearings that are in an environment where they get wet with every use, and I needed a special tool (circlip pliers) to get them out of the plastic holder. The shaft on the brush rollers is also steel and was beginning to rust badly.
I can't imagine that some engineer at Hoover is so dimwitted as to use those bearings and shafts in that application where they get wet every time the appliance is used, so he/she must have been overruled by the bean counters at Hoover. For the sake of engineers everywhere, I hope so.
But anyway, Hoover has been making floor care products long enough to know better than to use materials that will quickly corrode in a wet environment, yet they chose to do so anyway. Suffice it to say that the devil will be plowing snow before I buy another Hoover product.