JE, sorry you had trouble with your CM, mine works pretty well.
I don't use it for loads below 40 grains. A 40 grain load that varies .1 grain is only 0.25% variation, for anything but BR shooting, I consider that acceptable.
I check mine often with a Ohaus 304 scale.
Regarding the worse thing, would have the to be the Pac Scale/dispenser I bought about 5 years ago. Was supposed to be the newest and greatest thing. What a piece of junk. Extremely slow, and varied .3-.5 grains every charge.
They wouldn't stand behind it, so I put on Ebay for half price with note in all caps stating "it is not accurate!" Some guy jumped on it. Before I sent it to him, I made sure he understood what he was getting.
I consider myself lucky to have sold it, rather than trash it.