I'd say music played on mainstream radios is like this:
15%: Can't listen.
20%: Don't want to listen.
35%: Comes in to one ear, comes out from another.
10%: OK stuff, yet wouldn't listen it unless it came from radio.
10%: I like it, yet it's not too good.
10%: Great stuff.
And I'd say mainstream pop has gotten worse. And I think the reason is that current mainstream music is made to get attention. Deliberately irritating song (like all Lady Gaga's production) gets much attention, and music channels brainwash people to thik it's really good and worth buying. And add to that that no matter how bad a song you have, all you need is to look like a porn star and all wankers are your fans. And then your music is played even more on MTV, and also others start to think it's good music.
A great example on how pop music now needs to be spectacular rather than good is Black Eyed Peas. I really love their earlier production, yet their last two albums have sounded like another group. They're now only mainstream disco pop, music I don't like to hear. Obviously that has made them more popular, more people notice their songs and buy albums. It seems they didn't have the attitude they have in this song:
"All they want is boom, boom boom, boom..."
Well, the first single from the E.N.D. was Boom Boom Pow.