Programming, more so than many other fields, has a strong tradition of self-improvement and education. Tell any "noob" that they are an idiot for using bubble sort and they should have more than enough resources and know-how to figure out why they are wrong and correct it themselves. (Either they independently invented it themselves, in which case they are at least moderately clever and you just told them the name of what they created (what they should google), or they googled it in the first place so they should be able to google it again).

Is it best, in a controlled environment with both low signal and noise, to take your time and explain things in detail in a "civil" manner? Sure. That works great in (small) classrooms for example. In a public kernel dev mailing lists though? No, a fuck off should suffice. If the recipient of the fuck off wants more, they can seek it in a more appropriate place.

IRC is somewhere in the middle; usually civility or ignoring the person works best. This is particularly true since most IRC channels are fairly explicitly there for people who want to give or receive advice. I've only told someone who was seeking help from me on IRC to fuck off once, and that is when he demanded I talk with him on skype instead of IRC, and pressed the issue.

Edit: I suppose I shouldn't expect a civil response if I explain in a civil manner why I don't think civility is always necessary. Hoisted by my own petard perhaps?