Talk About Muck!

‘Talk of Paddy barke’s echo! Kick nuck, Knockcastle!  Muck!’

                                      (P: 378 L: 36-37 (379))

This reminds me of dirty mud (have you heard of clean mud) or a dirty castle, as compared to Howth castle which is supposed to be clean. Now I vaguely recall reading about a Castle on Loch Ness and that this Knockcastle is in reference to it, but that is the denotative meaning, I’m looking for inspiration and all I am getting is some Irish guy’s echo and kicks in the head! But perhaps that is what I am supposed to get from it.