Am I a good singer? Damn this needs to be 20 characters long. Why?

My friends and family for years have dubbed me as a terrible singer but I have a theory that even if I grow to be the best singer in the world they'd still call me a bad singer because they're used to it. I'm not asking if i'm a great singer but if you heard me singing in the halls or something am I bad enough u'd have to cover ur ears and yell for me to stop? Like my friends do :D anywho heres the link : http://www.youtube.com/watch?v=ExiZssUbloI also I have met singing instructors who think they could teach me to sing better so if you have any tips for improvement it'd be great.