Comedians sometimes see it as part of their 'craft' to push the envelope and toy with, (or go over) the edge. For some comedians, it's not about whether they made you laugh, but that they shocked you, disgusted you or provoked you in some way. Similarly, magicians often see their craft not only as performing an entertaining illusion or sleight of hand, but also shocking audiences with 'superhuman' death-defying productions (Houdini; David Blaine).
The reality is that sometimes comedians see it as their professional duty to break down taboo topics and if you look at careers of people like Richard Prior, Lenny Bruce or Andy Kaufman (to name a few), I beleive they set out (at times) to use 'comedy' as a vehicle to shock audiences -- sometimes for the sole purpose of shock, yet sometimes to make social statements, or get something they see as important on the table. A comedians 'pulpit' allows them through mimicry, satire, hyperbole, provocative languge/gesture to get issues out there that may otherwise stay hidden. Sometimes it's useless/senseless, but sometimes there is social value. I think good comedians are willing to try new things and push some edges, but are also aware that overstepping (in and of itself) isn't necessarily a badge of courage, but sometimes is a mistake. Good comedians probably have a sense for what is going too far, or what is too soon. Good comedians probably also have enough in their toolbox to recover.
An example of recovery (my opinion) is the GIlbert Gottfried example. For anyone who saw the Aristocrats (I believe it was this performace that the prior poster may have been refering to), Gottfried bombed with his 9/11 jokes -- bad taste and way too soon after the event. In Gottfried's defense, he read the audience and he abandoned his mistake. He went on to regain the audience with an impromptu (and hysterical by some accounts, depending on your appreciation of some grotesque humor) version of the famous Aristocrats joke. To his credit (my opinion), he acknowledged his faux pas, and quickly went in a new direction. Probably was stupid to go where he went in the first place, but comedians are human too.
I don't know about this Ross guy.