"What's all this 'red herring' and 'crimson kipper' nonsense? Maybe I'm being naive, but using facts, comparisons and examples to back an argument seems pretty normal to me."

Only when they're actually relevant.

Some posters (not me) have used these expressions because others are bringing in foxes killed on the road as an argument in favour of killing foxes by hunting and a whole lot of other totally irrelevant arguments in order to hide the issue of whether fox hunting in the traditional sense of that expression is cruel.

Frank L.
(Chairman of the Ban Tomato Picking, cruelty to fruit campaign)