How would a picture of you be defamation? It's also only a single incident so it wouldn't constitute harassment. If you're on their property they have a right to take you a picture of you. Distributing it for monetary gain would certainly be an issue but I don't think what they did is illegal at all.
But yeah, it is pretty gross to have your dog peeing on the sidewalk. You don't have a grass area instead?
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If you don't think you did anything wrong, then why would you consider what they did shaming you? If you do believe it's shaming you, perhaps you believe what you did is wrong.
I recommend the best approach which is to read David Thorne's email exchanges. Take lessons and troll them.
http://www.27bslash6.com/