HRE wrote:
Tell your wife that since she doesn't like the way you want to deal with it the problem is hers to solve which includes clean up.
I actually took care of this once by tossing one load back into the neighbor's yard, just the yarrd, not the roof or steps and that was the last time their dog ever bothered our yard.
This is a sensible suggestion.
The various revenge fantasies outlined in this thread are funny--I laughed in spite of myself--but they're also illegal most of them, and they're guaranteed to create bigger problems than they solve. Why do that? Isn't the idea to live in peace here, unmolested, rather than up the ante, creating new aggression, a new set of bad feelings?
The real question for the revenge fantasists is: How could you let a little dog poop lead you to behave so badly? I don't know about you, but I don't want to give a f-ing pooch that much power over me. I'm a decent guy. Damned if I'll toss that out the window for an animated hairball.
The hardest thing here is also the best course of action. You've said your neighbors are nice people. Take the risk of speaking to them, clearly and peacfully, as though you actually want to create community with them rather than making war with them. They probably don't know their dog is doing this. Enlighten them. (It's possible, of course, that they won't believe you--will think that it must be one of the other neighborhood dogs--and so it might not be a bad idea to take a photo, or, better yet, a little video, just in case they raise this objection. Don't bring it along for the first conversation; just have it in reserve, so you can mention that you've got it if they raise this objection.)
Rather than knocking on their door, you might wait until you see them pulling into the driveway or coming out the door or hanging out in their backyard, then ask if you can talk to them. Better yet, wait until you see them walking their dog, if they do that. That's an obvious opening for this sort of conversation. Then tell them what's happening and ask, "What can we do to keep this from happening?" Maybe you need to erect a fence. Maybe they can leash the dog. (Does your community have a leash law? Many communities do.)
Golden rule. Risk an honest exchange. Don't start off like Dirty Harry. That's silly, counterproductive, and illegal. Don't let the smelly little animated hairball (aka, their dog) get your goat.
You can escalate later (dynamite, ground glass, etc.) if need be.