In an earlier post here, someone stated there J came up to give them trips, but someone else caught there Q(who also had pockets). I can relate to that most definitely. Recently I was holding JJ. I was debating with myself as to how to play them. See, usually they are flat out losers for me as well.
I even call cause going all in, I always get a caller and get taken out 90% of the time. At any rate the flop is AQJ. Nice to see my J but naturally I'm afraid that someone else has hit their high straight. Still there's not much betting going on, so I bet my trips aggressively. Well no one had a straight. That's the good news. The bad news is someone did have pocket Aces and as you see from the mentioned flop, this gave them trips as well. Higher trips of course. With such light betting going on, I was sure I had that one wrapped up.
All this to say for me, JJ has been poker suicide. Play it and your hand/chances are dead, lol. But that's just been my experience. Again, looking at earlier posts, apparently JJ does very well for some.