We use them all the time. Send one out into crowded room of mobs, thru a door, around corners, down the hall, etc, and then TARGET your mark, and have cleric or chanter ASSIST you, then cast paci. Paci casts thru walls and around corners. Repeat until you have only the one you want to pull, and send in someone or a pet, and bring it back to be killed.
Works for more than scouting, if you use them to their potential.