What terrible traits do terrible players have in common?
They are the first to talk trash about your rank in a bot/aram game. Despite the fact that not everyone cares about ranked games, they will talk trash about your rank the moment you don't have a current rank history(despite having plats/diamonds in previous seasons since they can't see it without your current rank available). They are also generally bronze and silver, nothing wrong with bronze and silver but if you are a trash talking bronze/silver, then there's a problem. If you are one of those guys who quickly jump to talk trash about someone's rank, you better make sure you're a high diamond or keep that trap closed :|
Though being diamond and up doesn't give you a free trash-talk card either but at least you have some skills to back up that trash talk in comparison to having no skill AND trash talking about someone else's skills.