I don’t read usenet but I don’t think the issue is that the Japanese in mangas is bad; it isn’t. The thing, though, is that they’re written for a native audience. When you start learning with mangas early, most cultural references and connotations are lost on you. Essentially, it’s very difficult for a beginner to put the dialogue in context. That’s where you get people wondering if addressing teachers, in school, as -chan is common. Notwithstanding cckerberos’s school, it isn’t.
That being said, “live” material, meaning stuff that’s actually written for native speakers, is ten times better than textbook. If all you use are textbook when learning a foreign language, you eventually only become really good at reading textbooks.
I have to disagree with cckerberos on this. Lastname-san should suffice for a colleague, especially if the age difference is less than, say, 10 years. I’m a postdoc and it would feel weird to be called -sensei by a co-worker. (Though I’ve gotten used to vendors calling me that.)
There’s another odd little twist that should be mentioned.
You can use -san when you’re talking with someone within your ‘group’, or with someone outside your ‘group’. But when talking with an outsider about someone within your group, you don’t use -san.
Example: My manager (inside my group) is Kawamura, and our client (outside my group) is Fujino.
It’s correct for me to say:
“Kawamura-san, did you get a call from Fujino-san?”
and
“Fujino-san, here’s the latest sales report.”
but not
“Fujino-san, Kawamura-san needs you to call him.”
Even if Kawamura is a 1000-year-old CEO ninja master with 5 PhD’s and is elder brother to the emperor, because he’s part of my group, the correct way to say this would be,
“Fujino-san, Kawamura needs you to call him.”
There are all sorts of other cases similar to this, where the word or form of address used when talking about a member of your family or company is completely different from what you would use otherwise.