>>Come to think of it, it should be considered an art - it's an effect that isn't simple to achieve intentionally. It's a sort of negative diplomacy.
>
>It's a passive-aggressive behaviour. Unintentional I believe. Very subtle, but does leave you wanting to lash back.

Now you've said it better than I could. I'd only disagree with the "-aggressive" part, because I can't assign actual aggressiveness to it, but rather some spotty insensitivity.