As a screenwriting blogger, I get a whack of offers to review books from publishers and marketing people. As a book author, I've sent them out.
I've noticed I get much, much better results when I'm the one sending out my own publicity ("please help me get the word out") than when Lisa's sending it out as my publicist. (She actually is a former publicist.)
I also just noticed my own reaction when someone asked me to read their book. I liked the idea, and maybe I would have read it even if the email had come from a publisher. But I liked being emailed by the author more than I like being emailed by a publicist or a publisher.
So there you go.