I like GoodReads for a number of things — a place to record what you've read (or are going to read), a place to review and read reviews, it does well at that.
But a reliable place to get quotations? Pfft. They're all hand-entered, some from books but some from favorite bumper stickers and posters and Internet memes. Few of them have any citation or even reliable association with a book they are entered underneath.
That's not GoodReads' problem per se — as I said, it's a crowdsourced collection of quotations, and I doubt they have the staff to really scrub that stuff. Maybe a formal caveat on their part is in order. Regardless, take what you see there (in the quotation lists, at least) with a grain of salt, because that's the extent of effort that's gone into it.
Does Goodreads Care About Its Bogus Quotations? | Lev Raphael