Barrapunto

Así pues no veo el porqué de ofenderse.

porque "blavero" es despectivo (o así lo he escuchado decir siempre). Pero si me dices que no se ofenden, encantado, seguiré usándolo ;-)

no conozco a ningún negro que le ofenda que le llamen así,

Wikipedia [wikipedia.org]:
  From the 18th century to the mid-20th century, "negro" (later capitalized) was considered the correct and proper term for African Americans. It fell out of favor by the 1970s in the United States. In current English language usage, "Negro" generally is considered acceptable in only a historical context or in the name of older organizations, as in the United Negro College Fund, and is used more commonly by those born before the post World War II baby boom.