While I've always been one who enjoys a good argument here's where I see things getting a little foggy.

Suppose there is a given episode of Enterprise, say "Regeneration". People are giving their opinions of it. Some like it and say why - good action, good acting, explains continuity well, etc. Some don't like it and say why - poor action, poor acting, feels shoe-horned into continuity, etc.

No problem with that. Then someone comes along and gives an indictment on Berman and Braga, giving a litany of every sin they ever comitted. The problem isn't the opinion. Nor is it expressing the opinion. The problem is it is the wrong place for that opinion. It's off-topic. The conversation switches from the pros and cons of a given episode to that of the entire show. Not that such conversation shouldn't take place, just they should be in their own thread, not one about a given individual episode.

Same thing with politics in my opinion - a thread about whether Iraq had weapons of mass destruction could quickly turn into indictments on Nazi Germany, civil rights in America, or the evil Normans and the Battle of Hastings...

Keeping things on-topic in given threads would go a long way towards a good environment. (Not a criticism of the moderation - sometimes people need to show some self-restraint, as threads often gradually slip in that manner)