Useless tools? Not very many.
Tie rod sockets. I have several, courtesy of Dear Old Dad. I've never in my life seen a tie rod that had an adjustment. Must be a WWII military thing.
I can think of several disappointing ones, though:
1. Every rechargeable battery I've ever owned, in particular the ones exclusive to my two cordless drills. The drills were dead every time I needed them; and once fully-charged, would last almost long enough to finish the job. I would end up dragging an extension cord (or air hose) and using a real goddam drill; one having an external source of reliable power. With three or four times the torque, and one-hundreth the headache.
2. A "Vortex" device which accepts compressed air at the inlet in the middle, and dispenses hot and cold air at opposite ends. I have mostly used it to cool off in summer heat. The idea is that the cold-air end will chill automatic chokes so they can be rapidly re-tested instead of letting the car sit overnight. Great idea, not actually cold enough in practice.
3. Consumer-grade Chilton, Haynes, and other "light" repair manuals. They tell you how to do most of the stuff you already know, and fail to mention all the stuff you actually need help with.
4. The Harbor Fright air ratchet I bought in '84. What a weak-*** piece of junk. I could hold the socket with my hand while the ratchet head vibrated but didn't move far enough to engage the next tooth.
5. Every universal-joint or universal-joint socket I ever saw that used roll-pins to hold the thing together. Outright dangerous--they don't just fail, they explode, leaving sharp bits 'n' pieces that slice skin.
6. Cheap multimeters. What good does it do to take a measurement of something when you already know the meter isn't trustworthy?
7. Single-stage air compressors. Even worse: Single-stage air compressors that run off of a fifteen- or twenty-amp 120V outlet. They give good air tools a bad name.