Sabotloader - great post!
The only thing I would add is that often times the problem come not from discussing/debating the merits of one product vs another - that is human nature and healthy. The problem I see most often, and react to more then I should, is the predictable constant pathological hijacking of any thread to inject info on brand A when the question and discussion was specifically on Brand B. It then escalates from a discussion to a mud bog. And it starts almost exclusively from one source - a person back from a banning seeking desperately to be veiwed as an authority.