Every club? Really? See way more replica shirts at other grounds than at Anfield. I know because I laugh at all the fat old men struggling to stay in them
probably not every club but it is for most clubs, and not only in England but throughout Europe.
Looking "casual" is massive among the vast majority of regular/die hard fans throughout Europe. I know plenty of them and they have the same argument as people on here: "casuals"= regulars/hooligan element, "colours" = so called "derby fans", mening people who only go to big games.
One other thing I mentioned in the paragraph above - for the younger generation, who are 90% of the die hards or ultras, wearing stuff that people mention here - adidas trabs, black/dark jackets, caps etc equals being a part of the hooligan element of the support.
Casuals are another term for hooligans throughout Europe.
Liverpool of course is the birthplace of that look, although not the name "casuals" and I think it's a great tradition, just wanted to say that the style is very popular all over Europe and has mostly hooligan connotations.