I'd tend to argue that no language is worthless. First, a real programmer should be able to pick up a new language in a few days worth of study. Second, almost any language is bound to have some application worth learning. You might find in the future that some feature of a language you previously found obscure shines some light on a problem, and allows you to solve it in a more efficient manner.

Just my thoughts, though. You might find things to be different if pointed at Intercal or Brainfuck or Befunge.