We all try to look our best when a photo is taken. (In theory.) Unfortunately for actors and other famous people, paparazzi are literally under every rock. Pictures are taken every day of the week, every moment out in public, healthy or sick, bad hair day, happy or sad. And plenty of sleazy tabloids and website to buy those pictures.
Think of the worst day you've had lately, and imagine someone has pictures of you from it, and is passing them around.