If a dog poos in a forest...

Taking a stroll through the woodland in between Green Lane and Sir Joesph Hood Memorial Park the other day, I spied this eloquently-written notice pinned to a tree:

Nobody may be watching
but it is still disgusting.

Could you please

pick up after your dog

All of which begs the ancient philiosphical question: if a dog poos in the forest but there is no one to see it, is it still disgusting?