Tim here is my take on it. Regarding opposition fans going where they "should,nt" be, frankly there has been some precious posts in this thread by some City fans. Loads of blues have done this all over the UK and Europe. It is however only twats who do not respect that they are in an area of a ground where it is not only sensible but a matter of good manners to behave appropriately. Sometimes that may involve keeping quiet, sometimes it might be ok to cheer your team on....but you dont go in there wearing colours or indeed taking the piss in anyway. I am sure plenty of Celtic fans did behave appropriately and were welcomed by blues.
Regardless of which part of the stadium you are in, singing songs, chanting, flying flags that may involve offending the natives, such as those chants or songs that may attack our armed forces or indeed glorify a terrorist group that bombed and killed both servicemen and civilians in this country is not acceptable.
Infact anyone who feels otherwise should not even be in this country for any reason whatsoever in my humble opinion. Ironic dont you think that to even say such a thing can get you accused of all kinds of nonsense here in England these days, yet some of your support seem to be free to spout pro IRA bile. To compare it with singing songs about Munich is wide of the mark, after all Munich was an accident a totally different thing. Attacks on British servicemen and civilians were cerainly not For the record as someone mentioned City were not without loss in the Munich disaster, and the songs about it are moronic and have long since been almost universally accepted as such.