I quite like Fraggle's impression on status by feeding. Or perhaps it's merely good manners to lick another dog's arse and eat their feces. Do you suppose they're embarrassed by the human behaviour of shaking our filthy paws together?
"Hello Sparky! *sniff* Still on Atkins, I see."
"Still at it, Spot. Haunches have never felt better. What are you about today then?"
"Oh, you know, just having the human out for a bit of walksies. Seemed a bit morose so I dragged him off to the park. You?"
"Same, I suppose. Look, they're saying hello - no, no! let go of her paw, Steven, you don't know where that's - let go, get out of it you - oh for God's sake! I bloody give up. Go on, shake his hand, then. Why don't you give her a little air-kiss while you're up there - right, that's it, we're leaving. Can't take you anywhere."
Then again, dogs do (or are meant to) eat feces for vitamin K and the like (and not just to embarass their owners, as is commonly believed). Perhaps it's a bit of a taster's test to see what might be up on the menu in a few hours, nutritionally speaking.
"Well, that smell like a ripe bit of park chip there, Roger."
"Yes, I'm afraid I can't recommend it today, Arthur; had a bit of overripe sneaker the other day and it just isn't sitting well with me. You might try Daphne over there, I understand her owner has her on the NutriCal this season."
Or maybe they just bloody like it. Perverts.