I just played with my Warlock Zoo deck against a Warrior. I thought that it was a Control Warrior, which turned out to be a devastating error. It was a Grim Patron Warrior, and I delivered a perfect board full of Imps just when he was able to play the Warsong Commander Grim Patron combo.
Maybe this matchup is pretty much hopeless anyway, with Imp-losion, Imp Gang Boss, Haunted Creeper and Voidwalker I have just too many minions that are ideal to multiply Grim Patrons. But I wasn't all that far from being able to burst down his remaining health, so maybe it is not entirely hopeless.
But I need to recognize earlier if a Warrior is likely to be a Grim Patron style one, and not only after they played their combo. Are there any particular signs that indicate a Grim Patron Warrior and not a Control Warrior?