In today's generation, sincerity is very rare and they are the best. It's the mixture of seriousness, honesty and trustworthy, especially doing the part when no one is looking at. Being sincere is being honest but not in a bold and shameless way which will make others feel bad about an honest comment made about their looks or bad behavior. They are the ones who offer true love. Now don't take advantage of it because it will cost you great regret.