"Quality" and "useless" are both very subjective and very personal. I've read non-fiction that left me wishing I hadn't wasted my time on it, and been enlightened and entertained by fiction. My recreational reading is just that - for recreation, so if it entertains or amuses me, it's not useless. Whether it is fiction or non-fiction is irrelevant, although as it happens, most of my recent favourites have been non-fiction. I certainly don't believe that a fixation on "quality" of reading makes any more sense than a fixation on quantity.