Was discussed a bit on radio this morning. To me, booing is 'justified' in a range of scenarios:
i. When a player switches clubs by choice, other than to get more opportunities, fans of the former club (and, I believe, only that club) are entitled (obliged?) to boo - this is the Horne-Francis problem; to me, only North Melbourne fans can boo him. So Rory Lobb yes, Lloyd Meek no. Exceptions might be made if that player was a champ of the club and you don't begrudge him going elsewhere (would we boo Fyfe if he went somewhere next year in search of a premiership? Not sure. Did Hawks fans boo Buddy when he moved to Sydney? I don't recall especially, which suggests to me not really)
ii. The Andrew Gaff rule - this usually only applies to fans of the team on the receiving end of the perpetrator's actions.
iii. A player who has acquired the role of a pantomime villain - think Ginnivan now; Ballantyne, Crowley, Milne in years past). Small forwards and taggers seem to figure prominently in this group - we loved to boo the others, and we loved it when ours got booed by everyone else.
iv. Players who have acquired a 'dirty' reputation (perhaps linked to ii). Toby Green is the most recent example I can think of. Tom Lynch also seemed to be heading in that direction a couple of years ago. Booing in these cases is particularly appropriate if they are the beneficiaries of dubious free kicks.
v. A great player who seems to be your team's nemesis, and you end up booing mostly out of jealousy because you wish he played for your team.
Not sure any of the above applies to Buddy in any real sense - perhaps v? My main concern is that some folk will jump on a bandwagon and join in because they were told not to, and it develops into something with a sinister edge to it.