Writing notes in books aka graffiti?

Some of you may have noticed my new love for my local library and the interesting things they have been coming up with (ie/ blind date with a book and the local author showcase). I found another extremely interesting yet touchy topic on their website and in the local paper: Graffiti in the Margins!

I remember as a student in high school seeing so many people having written in books, underlining sections they wanted to remember and then thinking, "How could you do that to a book?" See the exmaple below of an old school book I found at my parents house (I think one of my siblings had to read it for school at some point and it never got returned?!?). 

After reading the article about why they are starting this new project (which was inspired by the book Life by Committee by Corey Ann Haydu - which I still need to read and have since added to my reservation pile at the library), I have to say I am intrigued. I'm a big believer in sticky notes to mark pages and I've recently started dog earring pages (the horror), so why not write in the margins your thoughts and feelings while reading a book? I'm not sure I can bring myself to try it yet, though I was tempted while reading If You Feel Too Much by Jamie Tworkowski since it had so many great quotes I wanted to remember and things I wanted to look up. I'm still torn on going back through the book and highlighting quotes and writing notes, but perhaps sticky notes will be all I can manage at the moment.

I kind of like the idea of being able to read what others were thinking while reading the same book. "The marked up books provide two different reading experiences, the original text, and that of the previous reader." -source 

PS I also like that they are starting with ARCs to see how the project goes. I just might have to give it a go and write a post about my thoughts on reading a book that someone else already wrote in and my thoughts on adding to the graffiti!

Sidenote: In my text books in college I did highlight like a mad woman. So much to learn and so little time. And I still have some of those texts kicking around somewhere. But I don't think this counts.

So my question to you is.... have you ever written in the margins of a book? Could you ever bring yourself to do it? Would you be willing to read a book that someone else has written in?