This is not even a considerable issue and we have yet to really see a screenshot or a source for such a thing. I have to agree with Divine that until a screenshot from anyone is actually posted, that this is nothing but hearsay. Also, there is no point bringing up words like 'poor sportsmanship', 'immature' or 'harassment'. It is nothing but player perspectives which is easily considered as personal bias on the subject.

As a point of view..
This is not a major league sport and is also not a life and death situation, many people forget this is a game and people are entitled to PvP the way they want to within means (obviously 3rd party programs are not within means). Even if you are being silly and compare the game to major league sports or even the working world, you can scarcely say that anything in life is without 'poor sportsmanship'/'immature'/'harassment'.
This is human nature, there are people who will do this and no amount of descriptive words will change it.