from whats been posted, i believe that the way it works at Sparta is that fans from this club have visited clubs around europe and have brought back scarves that are now on display...so its not necessarily just confined to clubs that Sparta have played..
I'm sure from amongst the ranks we would have our own ecletic mix of scarves from clubs from around the globe...?
On a ever so slightly related matter, in my local boozer, there's a whole collection of ticket stubs from a wide selection of sporting events across the top of the bar, must be over 500 by now.