My specific example is when I go visit my parents in a different state. It's nice to sometimes have access to passwords at airline sites (to make changes) or to simply just do my normal surfing and have access to forum passwords, email passwords, etc. I trust my parent's PC as much as I trust my own because I put most of their security products on them.
Exactly. I would trust my brother's notebook. But, maybe not my neighbor's.
I would trust Comodo, Verisign, or Thawte storing my personal credentials. But, probably not an anonymous developer who numbers it "Beta v.0.1, unstable".
The same can be said for your own personal computer. Just because it's "under your control" doesn't necessarily mean it's completely safe. In fact your own computer may be more vulnerable because you have a false sense of security. If you are super paranoid about security then the only safe thing to do is unplug from the internet and read a good book.

I don't trust books either. Only dogs, babies, and jello. Things without ulterior motives.
