When younger a good friend I knew, during a heated encounter while playing junior footy, called another friend the N word. At the time I thought nothing of it, because I don't think any of us in our group thought of our offended friend as anything other than an equal friend. We no longer noticed his colour or heritage ... he was just a friend. So it was quite confronting when I witnessed his reaction to being called something which offended him so greatly.
I tell that story, because irrelevant of why somebody is called a name or booed, sometimes we need to remember who the person is that is hearing it. Goodes has done plenty that I can internally boo about, but I could never boo him at a game of football given the possibility that it may be considered to be racially motivated.
It no longer matters why he is booed. What does matter is just how hurtful it is to him and related others. A hurt where there is no longer any argument to justify the reason for it.