Well you have to observe how often they value bet there mid/top pair or how far they go with overs [ex.AK,AQ]. Most times if your getting called by a normally passive player, yout J4 is beat. I think it would be alot different if you were OOP and holding AJ. Im still not to fond of this hand and dont usually play it aggr. but you will notice you wont be pushed off your hand as frequently as if you were holding your J4, and you can bet because you will value out of worst J's, mid/bottom pair.