I've bought enough crappy tools that I don't just have one worst:

1: Those little corner-rounding planes that Woodcraft and others sell
- totally useless. Their only virtue is that they don't cost much.
2: Ryobi detail sander - it's great for making your hand numb, but
little else. Thankfully it was a gift so I didn't actually pay for it.
3: B&D belt sander - the internal drive belt mis-tracked off the end
of one pulley, and chewed through the side of the plastic case after
about 2 hours of use over the course of 2 years.
4: Freud FT1700 router - built in above table adjustment stripped,
spindle lock broke, then motor died after about a year.

Needless to say, I don't buy Ryobi, B&D or Freud power tools any more
(though I still buy Freud blades and bits).

Regards,
John.