The point is just differentiating your behavior between what you call a "bad" or a "good" junior.

And from experience the difference is whether they want to learn (regardless of their skill!!) or not (i.e are they passionate or it's just a job?).

Passionate seniors get frustrated when they try to teach bad juniors, but there is no point on doing that, the problem was just that the senior was not involved in the hiring process...