Not worthless hands but you have to know how and when to play them. Few hands in hold 'em are automatic bet-or-fold type hands. Just now as I was typing this, I was dealt K-10, gave it a small raise pre-flop, hit top pair (10s) with my king kicker on the flop, and bet everyone out right there. Perfectly acceptable play for king-ten. You can play king-jack the same way, just bear in mind you'd rather make top pair with the jack than the king. It also has better straight possibilities than king-10.