I think being vague is more cowardly than saying directly to someone that you have a problem with who they are or what they are doing/have done.

That being said, public forums may or may not be the place for that... If it is, the standard has to be consistant; it's either not tolerated at all, or it's open season....

I prefer the free-for-all scenario myself, and recommend thick skin and sharp wit. In any case, being a jerk to someone you think is being a jerk makes you a jerk, so a structural analysis of your domicile might be in order before you commence to launching igneous projectiles.