We imagine that most of the time, being trailed by the paparazzi must be the pits — particularly if you happen to be a famous woman. Not only do the photogs pry into stars' private lives, they also keep the rumor mill in motion.Sometimes, though, the folks behind those telephoto lenses actually manage to capture some pics that their subjects appreciate. Case in point: Recently, Demi Lovato was snapped just as she was about to smooch someone. The moment will go down in digital history, as she wound up sharing it on her own Instagram account.The "Cool for the Summer" singer even went so far as to express her gratitude to whoever took the photo. "Thank you sneaky paps for a really really cute candid pic," she wrote. We guess sometimes it pays to have someone keeping an eye out for memorable moments.Our only question is: Is this mystery kisser Wilmer Valderrama or just a friend?