true. my opinio of brussels at least, is that it is very clearly divided in to classes. of course, i don't know all of brussels, but my impression was that there was the international and diplomatic class, which is not particularly wealthy, but very cosmopolitan, educated, and tend to live in nice areas. there is the "french" class of wealthy french and french-speaking belgians. this class also lives in very nice areas, and they send their children to the best "public" french-speaking schools. They tend to associate a lot with diplomats and themselves, and are very "preppy". there are the flemish speaking people, who are more of a middle-class, at least in brussels. there is of course the poorer immigrant population, mainly from morrocco. there is also the "farm" class, most of whom are flemish, but some of whom are french natives, or speak french. they often don't live in brussels, but in the outskirts. they'r the ones that bring in fresh vegetables, etc for the markets, which are then bought by those rich enough to afford them.
NB-these are just my observations from where i have lived, so don't take any of this as "fact"

also, definitely applies ONLY to brussels, if that.