For a comparison to another regional dress that has almost become a national costume, consider American Western attire. I've never seen a book of rules, and casual wear of denim jeans is almost universal, but you have to admit that, without some care, it is possible to get up a Western outfit so ridiculous as to invite contempt anywhere. At best you just look like a dude, at worst like a parody of a Hollywood cowboy likely to get punched out in any bar with real cowboys.