You can read the full quote from her in the Sun newspaper if you really want to.
Librarians have not all reacted positively to the comment. 'Annoyed Librarian' on LibraryJournal.com lists 5 reasons why lady Gaga could never be a librarian. Ironically her list actually manages to be insulting to librarians on many levels. Amongst the reasons (along with stuff about not filing things properly!): she's young and thin, she's fashionable and she's rich and famous at an age when 'most librarians are still failing in their first career.') And of course, according to some her image was created by copying a librarian!
As I am not especially young, thin or (whisper it) fashionable, and have... not necessarily failed at, I'd call it 'moved on from' ...various other careers, I can hardly quibble. But I'm not a librarian anyway - I'm a library assistant - so I cannot speak on their behalf.
I'm sure you can think of other reasons Lady Gaga is nothing like a librarian, but I've got one for the list: Those heels! She wouldn't last five minutes.
Oh, and I found this on YouTube... enjoy!