because others are stupid and much more advisable than ourselves
seriously, because it's easier to see a situation when you're not inside of it. it's also easier to clean/tidy someone else's house than your own. a friend and i have an "exchange program" ;)
because it's not about you. Believe me, i think other people know us better than we know ourselves because our eyes aren't directed to ourselves--it's always, always directed to others. That alone could answer your question.