To get irritated at others writing comments in books?

I would never write in books, one exception was recently when I bought a book to research while writing my own book,I underlined the important parts which were easy for me to find when needed.

+pollyperkins*, I was going to mention annotating musical scores, too. It is assumed you will do it, and you may well get into trouble for not having a pencil with you. I usually owned my scores, but if we were using borrowed ones, other people’s comments and instructions (if not rubbed out) could be quite enlightening! Sometimes funny, too.

Sorry, posted before I previewed. My poor eyesight prevented me from typing pollyperkins properly.

Definitely beyond the pale to write in or otherwise deface library books. I could not bring myself even to write in my own books of which there are many.
Exceptions would be musical scores as Grandma70 said or maybe your own textbooks other than that its a big no from me.
I have written to authors and publishing houses when there have been serious spelling and grammatical errors in books.

I too detest people who write in library books! Even if they use a pencil, someone is still going to have to erase their jottings.

Once I borrowed a textbook from the library that someone had used when studying for an exam. They had highlighted everything that they needed to remember with a fluorescent marking pen! Sheer vandalism !

As an ex-librarian it infuriates me when people deface library books, either by writing in them or turning over corners to keep their place or using them as coasters! I annotate and underline my own non-fiction books heavily because they belong to me and I’m unlikely to be lending them to anyone else.

Jaycee I think you have summed up my feelings. It does pull you out of the story. In the book I mention in my OP the reader had obviously thought they had a better grasp of English and grammar than the author. I found myself thinking, no you are wrong and the author is correct and getting cross about that instead of enjoying the book.

notice a lot of mistakes on kindle FREE books, but because they are free i just read through them. But i did find it annoying on library books with pencil marks and comments.

I have never come across that. I did write a message on fb and got corrected by a complete stranger 😀

Why do people turn a corner of the page to "save their place". USE A BOOKMARK that's why they were invented,

Yes but they disappear regullarly. I have about 10 - most of them lost somewhere in the house! But if its a library book I use any odd bit of paper.
A librarian once told me they find some very strange book marks from shopping lists to £5 notes and even a rasher of bacon once!

A rasher of bacon! It must have been in a Peppa the Pig book. Excuse poor joke, its the heat getting to me!.

Or perhaps it was Animal Farm.

I occasionally annotate books of my own, either to save time on rereading, or where I strongly disagree with the author. I remember savagely pencilling the chapter on A Midsummer Night's Dream in Jan Kott's Shakespeare Our Contemporary, because I disagreed wirh himself strongly. I had recently played Quince, so felt entitled to my point of view.

That’s the sort of thing I would do, grumppa.

I didn't realise this thread was going to be mostly about library books. I haven’t used a library for a very long time, so I was just talking about my own books. I also have some that belonged to my mother, and I love finding her occasional comments and corrections in them.

"himself strongly"?????? "him so strongly".

I volunteer in a small library and get annoyed when books are returned damaged or defaced. We rely a lot on books being donated so it's a shame when people's kindness is not reciprocated.
I just could not bring myself to write in a book whether its mine or from a library.

I do hate to see library books vandalised, though I have sometimes use pencil in my own property.

Sadly, as with everything, people who get a free service show no respect.

It seems a very long time since I borrowed a book from the library that has not been marked "discreetly" by regular library users.

From what I notice, people choose to put a dot over a particular page number, or monogram somewhere, often on the front or back cover, and they always use biro.

I assume they do it so they can check if they have read the novel before, or not. Whatever the reason it still defaces library property!