There is a difference between rational thought , logic and the way that people really think most of the time.
If someone commits a heinous act , shouts "I am blue" and commits another heinous act then states that he is doing it for the sake of his blueness lot of witnesses will associate blueness with the heinous acts. This will get reinforced every time that the same thing reoccurs.
There need be no proof that all of the blue are heinous act comitters The blue guys that are committing the acts want the association to be made and they are up front and public, there might be a grand majority of the blue nation that is simply quietly unwilling to do heinous acts , it won't matter if the heinous blue are energetic enough to outshout the peacefull blue.
Blue and heinous will be associated because they show up together a lot.\
This is a general principal not specific to the blue , think about your feelings of the KKK or communists or godless atheists or Guatemalans(reverse this if you are a member of one of these groups , it will work reversed) Did anyone ever have to prove to you that every single one of the group was equally heinous before you developed a negative impression of the group?
So next time the elevator door opens and you see that you are going to be in a tiny room alone with a bright blue guy , don't hesitate , go on in , the odds are greatly on your side , logically.