Why do some people say i'm attractive and other's say im not?

I've had people (people at my school / university, grandparent's friends and even one random woman in public) say or imply that i'm attractive, but i've also had people say that i'm not. I've also had attention from girls, some pretty attractive, but also girls who don't want to talk to me. So why is it that some say I am attractive and other's don't?