By tweakers I usually specifically mean methheads. And not the most stable bunch (especially compared to pot users), but having grown up around many I usually feel irritation and pity before I feel afraid in most cases. Depends on the individual 'tude. The vibe I've gotten from this guy the few times I've seen him is that he's a bullshitter...

And I'd love to hear any stories. I'm a habitual patron of public transit as well, though for a much smaller city (and because it's California, its impossible to get on a train without someone trying to sell you either bootleg DVDs or "trees").