PLENTY of Gagas' lyrics are downright an embarrassment and this is coming from a fan. (Not that Christina doesn't have her share of whack tracks but the ratios don't even out when you balance the lyrical masterpieces with the I Hate Boys.)
Christina is an underrated co-writer and she's delivered some brilliance, but I doubt she could ever write a song by herself like Gaga - let alone a good one.
She's probably more of a lyricist with the odd melody.
You should know that Gaga asked X to be on the remix, and that's via Carson's radio show. I doubt C/X would've even done the song if she wasn't paid millions to do so.