>Your reaction (as mine was) is that it is impossible to tell the difference.
If you pour the milk into the tea, the first bit of milk will heat to nearly boiling, scalding it and changing its flavor. If you pour the tea into the milk, you don't have that problem.
The health problem can be solved by using a non-dairy milk like almond milk (which is also objectively tastier). As far as snootiness, I really think it's just a matter of personal preference. I enjoy it either way, although it can certainly mask the flavor of bad tea.
With bagged tea, leaving the bag in the milk while the kettle boils tends to take away an aspect of bitterness, which makes breakfast tea taste extraordinarily lovely. Though, having recently discovered the joys of quality leaf tea made properly, I have to quantify that with "extraordinarily lovely for PG Tips".
Really? Can you tell that flavor with 100% accuracy if you are blindfolded and someone else has poured the cups? What chemical change in the milk accounts for "scalding"?
I'd hypothesize that that's a different effect. Orange juice is denser than water, so if you pour water into orange juice, a lot of it will float on top. If you pour orange juice into water, on the other hand, the orange juice will sink through the water, mixing relatively evenly.
By the same reasoning, tea should actually mix better if you add the tea first, since milk has about the same density as orange juice and tea has about the same density as water. But in the case of tea and milk, you just have to bite the bullet and stir it manually if you want to avoid scalding.
If you pour the milk into the tea, the first bit of milk will heat to nearly boiling, scalding it and changing its flavor. If you pour the tea into the milk, you don't have that problem.