I kept trying to swap bad things Duncan picks up on walks with all different sorts of treats and try to find a higher value treat he will actually swap for and drop whatever is in his mouth and finally by recommendation from the trainer we are seeing I found a high enough value treat in his eyes for him to drop whatever bad thing he has picked up on his walk and swap me! haha ... at least most of the time... still working on it! The only downside is I am carrying around 2-3 different kinds of treats - lower value/reward ones for some things and then the higher value ones for leave it, drop it / swap me for whatever you have in your mouth & recall