Oh come on. Justin Bieber is generic but Lady GaGa isn't? Have you heard some of her older songs, like the unreleased stuff? Most of those and her old stuff from The Fame were all the generic pop stuff you'd expect to hear from everyone else. She didn't do much to seperate herself from the mass of popstars around at the time until she released The Fame Monster (and even that was a bit unsatisfying). Justin Bieber might be a tad on the generic side of pop and R&B but so are most of the people working in the same field so it's not accurate to blame his music but not take a look at some of the other music out there that's also hot at the moment.
Well, frankly, a lot of what Lady GaGa produces isn't your "usual" music. It's poppy-sounding but it's well-written and not the crap like "OMG I'm a girl who wants LOVE but I can't have it" (aka Taylor Swift) or "Yeah, I love... things" (aka Justin Bieber).
And also, Lady GaGa has written about a number of deeper topics. Poker Face, for example, is about her bisexuality. It's deepness that songs from Justin Bieber or Taylor Swift lack.
If I listen to a song and can fully grasp the entire message of the song after hearing it only once or twice, the song is most probably just generic
garbage. And I'm sorry, but that's what it is. Music is poetry set to musical notes. Poems that are shallow are, frankly, boring.
Taylor Swift, again, as an example. I have yet to hear a song from her that isn't insanely shallow. It's all about love and lack of love and crushes and there are no deeper meanings to be found anywhere. Just "well, love love love when you're 15 or if you're just shy or maybe if you're just a regular girl trying to make sense of the big bad world". Bieber's about the same.
At least some of Lady GaGa's music can be analyzed to find a deeper meaning.
[Mandatory addition due to above comment]: If you like stuff like Taylor Swift or Justin Bieber, whatever. Everyone has their tastes, it's just that... people need to accept that there is such a thing as
bad music. If you like something that you can understand in about five minutes, then by all means, listen to what makes you happy. That doesn't mean I have to think the music you listen to is good.