I imagine this will be like most of the books published on sorority rush -- some helpful information and the rest is either
1) only applicable to the school where the author rushed
2) completely stereotypical
3) outdated
4) completely useless
I read one of the older books on rush (Rush: A Girl's Guide to Sorority Success), which was by a former ZTA rush chair at UT-Austin, and while it did include some useful information, a lot of it was common sense and a lot of it was applicable only to Texas and similar big SEC schools. And obviously, since the book was written in the 1980s, some things have changed since then. This book sounds like it will be pretty similar.
And in defense of Cosmo, Self, and similar magazines -- they have to pay their bills, and usually the companies selling products related to body image (breast enhancement and diet pills) are the ones offering them the most money. Usually, companies who sell spare car parts or football uniforms know that it would be a waste of their money to target Cosmo, so it's mostly the appearance-oriented companies that offer to sell ads to the magazine. If they didn't take money from these guys, they wouldn't exist.
Not that a world without Cosmo would be THAT bad . . .