Sampiro, I’m sure it happens - in fact, I guess people in this thread have said it happens, but it’s also mostly real ‘reviews’ on those small-time ‘literary’ books.
I’m more likely to post a review on Amazon, and on facebook, if it’s a smalltime/firsttime author than I am on East of Eden. It feels like it’s accomplishing more - nobody needs a review on East of Eden.
Also, I’m more likely to review a book if I’m blown away by it, rather than not caring for it. Often I feel like it could very well be not for me, but someone might like it. Also, it just feels jerkish. (On the other hand, for best-selling books that I actually hated, writing the most bitter review I can on goodreads is kind of fun).
So mostly good or stellar reviews for smalltime books is not, in and of itself, evidence of reviews by mom, friends, and sock puppets.
Best logrolling I ever saw was when Alex Baldwin wrote the first book in his Men at War series. He got a favorable cover blurb from best-selling military fiction author W.E.B. Griffin.
It was later made public that Baldwin and Griffin are pseudonyms for the same guy, William Butterworth.
This sounds familiar. Over Christmas, I had the worst film I’ve ever seen inflicted on me. Looking at the IMDb ratings, it has a weighted average of 4.2, but somehow has 14 votes saying that it is a masterpiece.
The blurb on the director is worth a read. It’s so obviously self-authored.