HP budget pc's
IBM Harddrives
Ultra brand DDR memory.
MSC routers
These are the products that I can remember off the top of my head, the only one I personally have experience with is the IBM hard drives, had 6 fail on me, and the ones currently in my rig work on the basis that if I dont look at them, they're fine. Also the rear connections are increadibly flimsy
HPs' lower end pcs' should be avoided like the plauge, friends of ours have non stop problems with theirs. I'm not sure if the same applies to their "higher-end" stuff.
Ultra ddr memory is definetly not good, another friend would insist on buying the cheapest ram, againts my recomendations, he went through 4 pairs of memory (he bought dual channel kits) before finnally replacing those with a good pair of corsair memory.
I was once unfortunate enough to buy an msc router, broke after 1 week, had it replaced, the replacement broke after 2 weeks, replaced again and it worked for a good few months, then it started acting weird and wouldnt always allow me to configure it and wouldn't allow me to connect more that 3 computers to it, didnt matter wich ports I tried, just wouldnt allow it. Fortunately it died a few months ago and I was able to replace it with a decent Dlink that I got a great deal on.
Well those are the only things that I can think of off the top of my head.\
HTH