Honestly Robin, you've got far too much time on your hands.
'Dog dirt' makes it sound like soil and thus less offensive. 'Droppings' makes it sound like a mouse. For 'muck' - see 'dirt'. As for excrement and faeces, you can start calling it that on the dog fouling thread if you like. I'll call them chocolate bananas.
I don't think your four letter words represented by 5 asterisks is good England either.