I searched and found a similar post, but realized after I replied that it was in the ZJ Forum.
I have a 2002 Grand Cherokee Laredo 4.0 with 150k. I have replaced the front, drivers-side wheeling bearing 4 times in about a year and half. The first one was a faulty Duralast bearing from Autozone and needed to be changed within 2 weeks. Autozone exchanged it for a another Duralast. The second one lasted about 6 months and I asked for my money back, rather than another Duralast. I went to O'Reilly's and bought a Master Pro bearing that lasted about 6 months. When I replaced the Master Pro a few months ago, I forgot where I bought the last one and bought a Duralast with the intent on taking back the bad one. I realized my mistake after it was installed and I went to grab the old reciept. I know, I'm an idiot. And now the drivers-side is grinding again.
Before the Master Pro wore out, the passenger-side bearing went bad and I replaced it with the more expensive SKF bearing. I have had zero issues with the passenger-side since then (~9 months). I followed the manual exactly on all installations and always torqued the spindle nut. Is the drivers-side just a case of using crappy parts and getting crappy results? Or is there something else going on on that side?