For Girls (& Others) is not a collection of collaged poems, found poems, or appropriated poems, and it certainly doesn't contain 80% flarf.
The "Preface" is ripped off verbatim from the original "For Girls," an antique etiquette manual. That's noted in the, um, notes. It's a lie though, like most of the rest of the book.
Some of the poems themselves, particularly in the first section, do contain borrowed language, sometimes phrases, sometimes single words, often period metaphors or imagery, but these are generally gathered from more than one source and any lifted bits are remixed/recontextualized to such a degree that I doubt they could be traced exactly. The only exception would be the titles in the first section, which are indeed phrases mostly lifted from the original "For Girls."
A few of the poems near the back are flarfy, which is not to say I'd call them flarf. As Nada likes to remind, flarf is not a technique (i.e. google results collage does not make a piece flarf, though some flarf uses that technique)--it's an attitude. The attitude in For Girls is prissy and satirical in the first section, and less consistent and more contemporary in the second.
OK. I just felt like clearing that up.