I can't argue with anyone so far.

Spartan T, I think we need to remember that "it's just that way" is often the way in other places. Why is Navy blue dressier than brown? Why are checks casual and stripes dressy? Well, just because.

Having said that, I can imagine the yellow hose with certain tartans, even in a formal or semi-formal situation. And, if there were other combinations available, I would imagine some of them might work- say bright red or royal blue or maybe forest/ bottle green. Most of the colors shown are "warm" or "soft" colors, which somehow are associated with the outdoors and country pursuits.

Don't ask me, I don't make the rules. I just break 'em.