Yeah - the only time, really, that anything like that would be even remotely appropriate would be in tracking, not mixing.
I've been listening to my iPod on a pretty cool pair of Skullcandy earbuds, which really do reject a fair amount of external noise (they're basically earplugs with speakers in them). I've actually been pretty curious to try them for tracking, as they should theoretically allow me to monitor at lower levels, making bleed less likely. I haven't gotten around to trying it yet, though...