Three carefully blurred pages of editing from a story I'm really enjoying and where I think the author is unmistakeably talented.
Imagine what I do to stories which I feel need a great deal of actual work.
Welcome to the bright and shiny world of having someone who is actually interested in getting the best possible results out of your writing. It is not your best friend's beta-reading.
It is also not deliberately unkind.
This is also eight times as messy as it needed to be as I'm in somewhat of a hurry, but as I'll be keeping copies for interpretation and the author is willing to put up with what passes for my handwriting? I'm not generally so terribly messy, or prone to the use of more than one color of ink.
[has totally not threatened to break out the highlighters and thus open herself to retaliation from the author]
Note: This example is not, nor does it pretend to be, 'proper' editing. It's far, far too much of a mess on my part for that. Luckily, the author is willing to put up with my nearly unintelligible commentary scribbled horribly in the margins.