are sublimals crap or do they actl work

idk it keeps showing up on my fyp this days and i asked my friends about it and some said it cleared up their acne and gave them good grades or sth and sone guys even said it made them grew a few inches. but ion know id believe it it they said it was a confidence sublimals or sth cz u act like wat u believe right. but ion know someone tell me, do they work? whats the real sci behind it?