Unsavoury scenes for sure, but I got the feeling this might be a case of English fans' reputation preceding them. Let's face it (and this is a generalisation) Spanish fans don't really go in for hooliganism to the same degree as northern European fans.
If you go around other people's countries for years chucking chairs, pissing in fountains and generally being a nuisance, that is going to have an impact on the way you are viewed. You get the feeling all the tear gas etc was given to police at the Liverpool end and they were probably encouraged to some degree by their superiors to show the fans 'who is boss'.
As said, I am not excusing the tear gassing last night, but putting it in the context of how English fans abroad are viewed.