What's the correlation between idols and brainwashing? First I shall tell you my opinion about idols. For me, an idol is someone who appears in media and has beautiful appearance. Idols are usually seen with attractive expressions, poses, and clothings. Basically they are delicious for one's eyes. They seem to always be there for you, entertain you with their looks, voice, and talents.
One thing about them is that, even if you feel indifferent about them at first, if you see their pretty face very often, their charm will get you and you will love them. (Note: you must not hate their personality for this to happen though, and sometimes the charm can wear off). It is not difficult to find their gorgeous faces, especially on the Internet where you can download their digital pictures. Then you can view it anytime you want, or even set it as your desktop wallpaper.
Psychologically when a human often encounter another, a familiarity feeling will develop. It is not limited only in physical meetings. Viewing someone's photograph or picture, or even just by imagining them can make us feel more familiar with them.
When viewing an idol's picture, we are fooling our subconscious mind, which thinks that the picture is the person him/herself. When watching them on TV or other recorded materials, our subcon thinks that we are actually interacting with them. When listening to them when they share their stories, our subcon thinks they do it personally to us. And so on and so on. In the end, after repeated occurrences, our subcon is convinced that they are close and dear to us. Our conscious mind can still grab the reality, though. I call this phenomenon a mild form of self brainwashing.
Similar thing happens when we are accessing information from the media. We get a lot of information, some are factual and the others are mere opinion and views. But whether it is the truth or not, the more we are exposed to these information the more we think them as the truth. Even the most fabricated news can seem like it is real.
Many people are visual, they think what they see is the truth. "To see is to believe", they say. So they believe almost everything they watch on TV, where usually they do not even bother to think. Similar thing happens with other media. This makes it easy for people who have access to the media to influence those people. Sugar coat it and broadcast in as often as possible, and voila, you have "the truth" on the tube. I call this a form of brainwashing by the media.
In the case of idols, most of the time our conscious mind still can differentiate what is and what is not. We just want to make believe. But in the case of the media, we do not know which one is and which one is not. And we are made to believe.