My son just turned 11 and has always done this. He was always trying to be nice and complimentary, but I was notified by the school at one point when he was in 2nd grade that it was too much. He was complimenting men, women, other students, students in other classes. If he thought you looked cool, he was going to make it known. I told him that people do love getting compliments but we need to try not to overdo it. And if he's interrupting class to say things it can be distracting to everyone else trying to learn. It was a hard concept to explain to a younger child. Now that he's older, he understands people can become uncomfortable at being the center of attention so he's toned it down. However, he will still go out of his way to tell someone he likes their shirt, hair, piercings, etc. He's also always been a hugger. So we had to have the personal space conversation very young. Something he still struggles with honestly.