Amos didn't catch the blush, and wouldn't have inferred much from it if he had. But had he known that his honest compliment had any effect on her at all, it definitely would've been a positive feeling. There they were opposites in some ways - while Genevieve was prone to sharing her feelings, Amos lacked much of the vocabulary to do so, even if he felt it was appropriate. He still experienced the feelings, of course, they couldn't take that away from them, but the beyond the basics, the words were lost to history.
He also hadn't expected such a lengthy and detailed answer, but he liked it and found himself smiling at her, even through the confusion at a few of her words. And then she got to the last bit, and suddenly he completely understood.
"Yes, I heard about the sunbathing, too! What, you just lie there for an age doing nothing at all? For what purpose?" he exclaimed. "I don't know what the muggles are though, or what it was you shouldn't do in front of them," he added, almost apologetically.
"It's so good. I've never seen so much green before, and the ocean, and the people - they're all outside, talking to each other, I even saw some people dancing. In the street, just dancing!" he told her, as though it was the most incredible sight in the world.