This just popped in my head, wondering what to say if a JW came to the door. If you asked them politly to take the trash out (You bring it to the door for them so you don't have to invite them in), would they? They are there to give a good witness, right? It could go on like this:
JWs: Good morning, i'm so-n-so and this is my friend blah blah and we're here to.......(let them finish their sales pitch)
Me: I'm not really interested right now, but hey, since you are going past my garbage bin, could you take this bag and drop it off for me?