My neighbor loves to organize wine tasting session with friends, one day, he opened some bottle, and when I poured it, I added some apple juice (about 50%) and

My neighbor loves to organize wine tasting session with friends, one day, he opened some bottle, and when I poured it, I added some apple juice (about 50%) and nobody in the group noticed anything. I know that a few expert can actually tell wine apart and categorize them, but I now know that most of the time people have no idea :)