Well, I don't use public computers much anymore since I just bring my laptop with me, but I might go to SF on a public computer in incognito mode. I do log in to the site on my laptop when I'm in public when people might be able to see me. (I know the actual name of the site is not displayed prominently, but I still get kind of nervous that someone will see.) But actually, even on my own computer, I only use SF on incognito mode for some reason, even though nobody else ever uses this laptop. I don't know why I do that, and I feel like I shouldn't but I don't feel like having to explain it to someone.