Stiletto steel hammers- I've worked with a few guys that had these, and every one of them had trouble with the handle breaking. The same problem doesn't seem to be apparent with the titanium hammers, but the steel hammers must have the weakest handles ever.
PVC air hoses- need I say more?
8" Dead On Exhumer- the way that the claws are setup makes it really easy for the nail to slip out of the claws while you are prying. The larger one that I have has a slightly different head design and works really well, but the smaller one is junk. Oh, and the dimplier and bottle opener on all of them are pretty much useless.
This is interesting though, because quite a few of the things mentioned have worked just fine for me in my experience. I only own one Kobalt tool, a framing hammer, and it works great. Rigid cordless has always treated me good, and so has every Makita Recip saw and grinder.