Kaimax wrote...
Otaku originally means "another's house" or "family".
In it's "slang" form ,it literally means a "geek", and otaku doesn't have to be related to anything "japanese", anime or games. If we literally translate it again it would mean "someone who's obsessed about a certain hobby", Like "movie buffs" or "bookworms", but in Japan they can call it an "Eiga Otaku" or a "hon Otaku".
Is it dirty, if I was a Star Wars Otaku? Is it dirty if I'm a Marvel Comic Otaku? Honestly no, it's just shows that I'm a big fan of Star Wars and Marvel Comics.
So, Otaku itself is not a dirty word. IT becomes dirty depending on subjective views.
Wikipedia is enough if you want to know more.
Plus I think that being raised in a certain culture permanently colors your view on the world due to being raised in that particular culture. I know theres some official sociological terms for it but if you think about it "otaku" in the US is pretty much equated with being a "geek" for something which these days is a good thing while being in japan, otaku takes on a different meaning as you said