Kind of a misleading title, isn't it? It's more about you soliciting a review for your book and not so much a discussion thread for people who enjoy reviewing
I review at least one book a week on my blog. Right now I have a bit of a backlog of TBR books and I pick among them depending on my mood that week (this past week I was sick so I needed a short book---one I had planned on reviewing got pushed back because of this circumstance). Authors do email me, and I turn them away if the book is not my thing. I will also contact authors myself if I find out about an interesting book on my own. Some authors make it harder than it needs to be to track them down, which is their loss
And my reviews are not always glowing
If a book is very bad, I won't review it because I won't finish it (life is too short to spend it reading very bad books). But most of the time I do have constructive things to say and I am not shy about it. I do the reviews more for the readers than for the authors