In responding to Andy Matuschak on how books fail, Arnold Kling details how he reads:

I have pointed out that I read a nonfiction book with an eye toward reviewing it. As I read, I am thinking in terms of summarizing each idea in my own words and of coming up with a critique.

There's no reason to limit this to non-fiction. We're always curious about how a story or idea works, so as we read we pull it apart and put it all back together over and over again, seeing if the re-assembly works better than the original.

Looking at Kling's and Matuschak's posts, both come across as too negative: Kling snippily points at Matuschak's tendentious prolixity, and Matuschak in trying to burn some books instead arsons his own argument.

To be fair to Matuschak, it seems that he does care deeply -- it's just that he's been in the trenches for too long and has seemingly forgotten what made reading enjoyable in the first place.

Readers are always guessing where the words will go next; hastening through sections where their predictions are spot on, and slowing when wrong.

Good writers make that path enjoyable for many different readers, varying the speed, the roadside attractions, and the road itself. By the time we reach its end, we find the core ideas explored, and those who were looking carefully will have seen a lot more.