I read somewhere that you can only see ghosts in mirrors and you can't see vampires in them at all.
This made washing my hands in front of the bathroom mirror at night very tricky as I'd have to stare into the mirror checking for ghost and whip my head around every few seconds to make sure no vampires were sneaking up on me.
A childhood belief about mirrors

others believed things like this
- If you stare into a mirror in almost complete darkness, the devil will appear instead of your reflection.Anon
- when i was young i used to believe that my image on a mirror would come to life if i broke the mirror.Anon
- I'm scared of mirrors because I think that there are ghosts in mirrors— est
- when i was small i use to believe my parents were vampires— marine student 4
- I used to believe that the people who take your blood at the doctor's office were vampires. — Andy
- I used to believe that if you slept with the covers covering your neck, vampires couldn't bite you. — Moot