Well - we know people don't always tell the truth, and we know propriety inclines most people to not say thing to us that might offend us or hurt our feelings, so, if someone tells us to our face that we are attractive our first assumption could reasonably be that the information they are announcing may not be accurate and that they are just being nice. To me, the real, or more significant or telling questions are; why do we care so much about appearance, why do we care so much about other's opinions, and why are some inclined to unreasonably diminish themselves while some are inclined to unreasonably advance themselves?
Often it's not even a matter of diminishing or advancing yourself, it's simply changing what you are to what others are - girls with long hair cut it short while girls with short hair wish it was long, brunettes dye their hair blond while blonds dye their hair brown, tall wish they were short and short wish they were tall, etc, etc . . . meanwhile there is always that very unattractive girl who promotes herself as 'all that' or 'I could be a model', etc. None of it makes any sense yet so many dedicate so much of their attention to appearance. I mean, I don't want people to think I'm ugly, I'm glad I'm reasonably presentable - but I just don't see the benefit of giving any attention or effort to caring what others think of my looks . . . now, if people thought I was a racist, talked ugly to my wife, or kicked my dog, etc, I would give attention to that.