I used to occasionally get a sulfur quality in my rootbeer. This only happened when I was priming the stuff with yeast, these days I force carb. I used ale yeast and would still get this issue. I believe it was yeast related, possibly temp related. I'm not sure what it was. I moved on to 2 liter bottles and Carbonater caps. So, I never bothered to look into it further.
Of all tyrannies, a tyranny sincerely exercised for the good of its victims may be the most oppressive. It would be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated; but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience. - C. S. Lewis, English essayist & juvenile novelist (1898 - 1963)