Well, I would imagine that most people have eaten fresh meat and milk together (even a cheeseburger sort of fits that). The thing to try would be spoiled meat and spoiled milk together. Problem is there's no control there (you eat it and get sick, ok, but maybe it was just the spoiled meat and the milk/meat combo had nothing to do with it).
So aside from the fact that it wouldn't be a very good thing to try, it seems that a meaningful experimental procedure would be tough to come by (unless you find lots of people willing to eat spoiled food).
Alas.