That's a pretty bold statement. Brainwashing is, afterall, mental manipulation of unwilling persons. It seems crazy but research shows exactly this. Here's how:
1) Play it again (and again)
A research study in 2011 by fMRI showed that repeated exposure to a song caused emotional centers of the brain (including the ones that show happiness) to react when they hear a song that's been played before, even when it's a song the person says they don't like. In fact, your backstabbing brain will show pleasure when hearing a song it doesn't like but has heard before more strongly than when it hears a brand new song that you *should* like based on your preferences. Ask yourself, what songs did I totally hate when I heard them the first, second, third time… and now I find myself singing them?
2) Peer Pressure
Besides your brain sending you neural signals of “me likey!” even when you don't like the track at all, there's more at work. The job of artist managers, PR firms, and advertisers mission is to make sure as many people as possible are talking about and playing a track. They send it to mailing lists of hundreds of media outlets. And the more it is posted around because it's new (not necessarily because it's good), the more people will assume it's popular. And a song being popular is the second most important thing to manipulating you – because of human's drive to fit in. When we observe that a song seems well liked (and people must like it, because it's playing all the time, right?!) we feel that not liking it must mean we're wrong. And while some people thrive on being contrarian, most people tend to drift toward liking the same things that everyone else likes. The idea that the song must be well liked is reinforced by the fact that social media, radio stations, the internet radio, and music blogs are all parroting the song at you. And then it's being played over and over. And this is where we return to point 1.
3) The Mood
The last way that the music industry tricks you into loving their suckass song is by influencing the mood you were in when you heard it as much as possible. If you're happy or a little tipsy, you are a prime target for liking music that isn't really that good. Especially if you hear it multiple times, with friends. While the human memory is a very complicated thing, the key points are that things like sound, taste, sensation (touch) all add vibrancy and resilience to a memory. This is why people who eat something and then have a bad day… never want to have that food again.
A perfect place to hear songs for the first time is at a festival, which is why so many DJs build their fanbase and release new tracks there. There's the fact that you'll hear the same song, or versions of it, played again and again. You're with friends who are hearing the same things you are (and about 100,000 strangers as well, which certainly gives the impression that the song must be really popular). You have camaraderie and booze and a beautiful sunset and possibly drugs. You are basically guaranteed to like the song. Your brain will be screaming I LOVE THIS SONG. It's probably impossible, after that night, to remember that you've always hated that song and the DJ playing it. Of course, if a song is played too much it does achieve a saturation point – where just the first few notes of it will make you want to set the world on fire. It kind of makes you wonder though, did I ever truly like that? or was my mind just being manipulated?