Over the years, I've bought maybe half a dozen books from Alibris. I don't know what special sauce is in the algorithm they use to generate sale emails, but it consistently suggests stuff I actually do want to purchase. The last email I got from them was perhaps too good--every single book was one I own or used to own: Katharine Graham's Personal History, Patrick Dennis' The Joyous Season, The Joy of Cooking. And Tuesdays With Morrie, which I donated to Goodwill when I became annoyed with Mitch Albom. I'm sure he totally felt my opprobrium.
Meanwhile, Amazon, which has received a ludicrously high proportion of my disposable income over the last decade and thus should have enough data to send me what I want for breakfast before I know I'm hungry, continues to send me ads for athletic shoes and blue jeans. (Nothing wrong with either, if that happens to be your bag. Just sayin', in my case, direct marketing fail.)