Imagine you make a PF looking for a melee job and someone joins on MNK, but switches to MCH without saying anything. You would be disappointed to find you entered the raid one melee shy. You might also be a little upset with the guy who deceived you.

Well, let's suppose you put in the PF comment "no bonus message, please" and you enter the raid with a bonus message in your face. You would be disappointed, and perhaps a little upset that one or more people deceived you--or can't read at least.

PF leader sets the conditions for the party. If you want the conditions to change, just ask the leader. You have nothing to gain by very obviously tricking the party; you will instantly sour everyone's first impression of you and risk getting your butt kicked out of future parties on sight.

I don't know how the forums made this so complicated.