In that regard, Aloysius was entirely right in his judgment of Barty, even though Barty hardly considered himself sheltered. As much as Barty engaged in the Dark Lord's work and as much action as he had seen of that, he was rather ignorant of most of the so-called real world. True, he understood the simply practical things, such as the fact that he needed his exasperating job in order to keep his tiny flat, but several things were just entirely lost on him -- like why some people insisted on being crude or crass, or why anyone would engage in sexual intercourse if not for procreation. It all sounded disgusting, if one considered the mechanics; Barty couldn't imagine anyone actually wanting to get involved with it. Honestly, as far as he was concerned, it was a miracle that the species had survived as long as it had.
While Aloysius went on about Nagendra, and Pepper, and Parseltongue, Barty considered the milk and sugar, but ultimately chose to take his tea black as well. He was much more fond of mint tea than Earl Grey, but he rather preferred the flavour of any tea when it was not diluted by the addition of anything. "I don't mind, sir -- Aloysius." The slip was genuine, as was the sentiment. "I like listening to people talk, really. My grandfather's always said that that was more why I could take History of Magic to NEWT-level, more than interest in the subject itself."
The notes about Pepper and Nagendra merited a bit more thought over a contemplative sip of tea, though, and Barty finally replied, "I know what you mean. ...I mean, I haven't ever had a snake, but... I like learning things and it really is a bit disappointing to know that there are some things that it would be impossible to learn."