Coalition, no everybody does not have to agree what the words mean at all!
For some, the word will mean 'poor', for others it will mean 'anti social, thuggish' etc, and for others all it refers to is a manner of dress.
I don't think it's at all snobby to observe the humans around us and comment on how they look and behave. It would be a sad day when we didn't notice life's rich tapestry imo.
If it's ok to jokingly say rah becuase it doesn't cause you yourself personal offence, then how can it not be ok to apply other words to other types of people?
Snobbery comes from all directions. I was labelled as all sorts when I was a kid, for being articulate, doing my homework etc, by kids who thought I was lesser then them (ie they were tough and cool, I wasn't.)
Why is it so much less offensive to attack and label people who might be seen as higher up some kind of social ladder then to label and attack those who might be further down it? A snob is just somebody who thinks they're better then somebody else, and many of the kids who thought they were better than me at school would fit the common usage of 'chav', not that we had that word then.