Conditional kindness. You know it when you see it: someone is kind only when they need something; someone is pleasant only with their superiors while they abuse those under them; someone is sweet-as-pie with their friends but caustic with service workers. You know the saying: What goes around comes around. You don't know what others are going through, and you don't know if your paths will cross in different circumstances. Be kind to everyone, if only because it's the right thing to do.