I don’t want to go over particular threads (and stir old feelings), but the example you chose is one worth examining for a quick moment hoping it won’t derail the thread into a rehash. That black people are loud might be right or wrong but it is a common enough stereotype that, as some pointed out in that thread, a line of humour has grown around that idea. Once the OP is set straight in that his observation doesn’t contitute an universal truth, that stereotype can be examined and debated to whatever conclusion might be reached.
I can’t think of a particular thread where the matter was framed correctly, but (except in the most egregious cases of bigotry fueled posts) why not take a poorly stated thread and try to salvage it for what little might be worth in it? If the post is made in ignorance, why not fight it instead of roasting the ignorant?
I can list some (hopefully not terribly offensive) stereotypes that are held in Venezuela (I realize they might not be as widely perceived in the US) to pose example of issues that could be reasonably explored with their respective possible explanations that dispel the myth while acknowledging that the stereotype is not completely baseless:
“Jews are smart”. There are some socioeconomic factors involved and they mostly go to jewish schools with kick arse budgets, facilities and teachers.
“The Portuguese don’t ever take vacations / have a great work ethic”. They mostly arrived post WWII and started their own service businesses where their busiest days are holidays.
“Farmers are lazy”. They wake up at 3:00 am and do their work while you sleep. When you wake up, they are dead tired and resting for their next work stretch, closer to sundown.
Generalizations don’t necessarily have to be wrong or offensive. If someone says that “white men can’t jump”, one could come up with a bunch of examples of a “white friend I have” that can jump non-tiered buildings in a single leap.
That doesn’t make the observation completely useless though. We could take a look at how that statement comes from the basketball culture, where black players kick arse and ponder how some of them come from ethnicities where muscle mass is better distributed than in our prevalent “white” ethnicities (I am not saying that any of these is true, just parrotting some conventional wisdom)
If I state that the worst black jumper ever can still jump circles around the best white jumper jumping from the shoulders of the second best white jumper, I open myself for ridicule, of course. It takes only one counterexample to prove me wrong and anyone can come up with one withour even looking. One needs moderation in how one states one’s perceptions.
I guess my point is that it is possible for groups to show distinct characteristics and that discussing them doesn’t have to be taboo as long as it is done with due respect and allowing for the exceptions that are bound to be there.