I think the problem like anon said lies with people having come to accept what goes on. The more they accept the more those that do this kind of thing do untill they are doing what once we would have hurt them for doing.
Untill the general attitude changes (or those that are offended speak up) no lines will be drawn anywhere.
The said truth is that there is no line that we can define and say this far and no further. All we can do is voice objections to that which we find objectionable. What we are doing when we do that is we push the definate grey area in a specific direction rather than allowing it all to become grey area.