"have a word" with any local waiters or shop workers who are wearing liverpool shirts ?

Well I do.

First night there, having a mooch for somewhere to eat, and I see this local in a Liverpool shirt trying to entice people into his restaurant. As I get closer I make eye contact with him, and walk towards him.

I then tell him in no uncertain terms that because of the shirt he is wearing he will not be getting my custom, and advise him that for many English tourists that shirt would put them off eating in his restaurant.

He looked slightly bemused, but I think he got the jist of what I was saying

Perfectly reasonable behaviour on my part I'm sure you will all agree, but oh no, the missus throws a wobbler, tells me I should grow up and that there is more to life than United etc etc etc.