Oh dear Bird, I hate editing.
I have been stuck in that special place called Editing Hell all year.
It's been worth it. I have three novels and a short story currently out, two more novels and two shorts forthcoming before the end of the year.
What bugs me most? The time. The time it takes to read a novel for the fifth time (that's four novels I can't add to my 50 Book project list!) hunting out stray commas and missing words. The time I'm not creating, despite screaming muses.
On the other hand...I've read half-edited books.
Even well-edited ones occasionally miss something.
The last two mass-market paperbacks I bought had editing errors, but only 1 per book. It was a your/you're confusion for one and an its/it's.
My favorite bit of bad proofing is a priest telling his acolyte to "light the censors."
And that is why I edit. So no one can say I don't know