Swift wrote “Mean” in response to music critic Bob Lefsetz, who gave her a cruel review after a February 2010 performance with Stevie Nicks. Lefsetz claimed that Swift “can’t sing” and that the performance “shortened her career,” but she ultimately proved him wrong.

"The song "Mean" is about, well, when you do what I do, which is you put yourself out there for a lot of people to say whatever they want about it, there are a million different opinions from a million different people.

I get it that not everyone is going to like everything that you do, and I get that no matter what, you're going to be criticized for something. But I also get that there are different kinds of ways to criticize someone. There is constructive criticism. There's professional criticism. And then, there's just being mean. There's a line that you cross when you just start to attack everything about a person, and there's one guy who just crossed the line over and over again. Just being mean, and saying things that would ruin my day.

This happens... no matter what you do, no matter how old you are, no matter what your job is, no matter what your place is in life. There's always going to be someone who's just mean to you. Dealing with that is all you can control about that situation, how you handle it. "Mean" is about how I handle it, and sort of my mind set about this whole situation." 

-Taylor Swift