Your post inspired me to visit Merthyr a few days back in search of the miscreant. It took two minutes to locate him. He was stood at the entrance of a shopping mall wearing a red Big Issue bib, black bobble hat and, as you said, a fecking Liverpool scarf. "Beeg Eeeshoe" he kept repeating to those passing. "I'll Big Issue you now," I thought. This is how the somewhat one-way conversation went:-
"Beeg Eeeshoe".
"Feck off".
(He gave a confused look.)
"Beeg Eeeshoe".
"Go feck yourself".
(His eyes widened as he glanced at my Cardiff scarf.)
"If you want more sales, try wearing one like this or even a Merthyr one."
(The penny dropped. He removed his scarf and held it out to exchange.)
"You cheeky kent! Who do you think I am, fecking Sludge?!"
(Those remarks confused him further.)