I adore indie novels. Even with errors (which I highlight on my kindle, or correct on my tablet,) they're awesome. But if it's something with advice or instructions.. it kills the message.
They don't really bother me most places. Even if I've paid for a book, (which is frequently a continuance on a free-first-book novel,) if it's just plain fun, it's not that big a deal.
I note it, but I find that slightly silly to do anyway. It doesn't really matter unless I actually get the chance to point it out to the author (which I don't, but hey, I'm prepared!)
But I was just reading a blog about running.. and I got to a "who's" that should have been a "whose".. and I just couldn't see the advice in the same way. Grammar shouldn't have that much of an impact..
I have the same problem, have always been hyper-sensitive to spelling and syntax errors. Sadly the career of proofreader was discontinued, I was born for it
I don't even mark it when its my housemate's book, but I might take note in that case just so when he goes and edits it, I can add it to the 'don't forget this.'