If they have a low self esteem it could make the mood bad and spread to the other person eventually, it can also lead to depression and high self esteem brings positive vibes to everyone, but you don't want too much of it or you could seem stuck-up, if someone tries complementing your dress don't go oh well I'm too fat in it, or yeah it looks so good on me, no one else it would look good on. Just say thanks! And give yourself complements if your feeling down :)