"Emo sucks" is a statement of fact in the same sense as "oxygen is good for breathing." "Emo sucks" is now the modern version of "disco sucks," with the all-important distinction being that enjoying disco in the nostalgic, silly sense is fun, but emo will never be cool.
Teacher: "Class, can somebody give me an example of indisputable fact?"
Student: "Emo sucks!"
Teacher: "A Plus!"