We lurk on the threads, for example, where readers discuss their reasons for deciding to DNF a book (do-not-finish). Extremely illuminating.
Other than that, as AW mentioned, GR seems to be minefield, and now, obviously some of the current drama will add to this sentiment on the part of both authors and readers.
I tend to lurk, too. There is behaviour on both sides of the divide, that has over sensitised everybody.
There is a group that has a thread to discuss my series and a reader asked me to join in. I declined, I said I would prefer they could freely discuss it without thinking I could potentially pop up at any time and gnash my teeth.
It's great when readers want your participation but you have to be so careful. I prefer to be over cautious and avoid anything that mentions my books. If readers want to toss stuff back and forth with me, they can find me on my FB page.
As a reader I love Goodreads, and the fact I can check out my friends' reviews on other titles, to see if I might like a book before I buy. It's a great word of mouth tool.