Now, I'm not equipped to perform a statistically valid sampling of all conference talks, but pervasive anecdotal evidence lends credence to this notion.

Specifically, this comes to mind:

http://lifehacker.com/5859392/swearing-to-make-your-point-a-...

As well as this:

http://www.zedshaw.com.sharedcopy.com/rants/51489cec9386f7c1...

And this:

http://david.heinemeierhansson.com/posts/15-potty-mouths

There are more, but I don't think I need to internet-sleuth the entire set of well-known Ruby / Web personalities to demonstrate the point: a base lack of professionalism abounds.