Apropos of nothing - a random HP thought.

[ridicully]

Where does half the fandom get the impression that Harry is cheating by using a book with notes in it?

They are allowed to use their book while brewing and are supposed to have read up on the potion they are preparing in class.
And in written tests, I doubt they are allowed to use their books anyway, so the notes won't be any help to him there.
The only difference I see between Harry and a Ravenclaw (in this instance) is that the Ravenclaw would have made the notes himself - and probably not in the book, but on a spare bit of paper.

Having better reference material is rarely considered cheating. No matter how much of an advantage it gives you.

Comments

[moira-can-bite.livejournal.com]

I think that it could be considered cheating because he takes credit for the potions. Slughorn is impressed because he assumes Harry is using the same instructions as everyone else but still doing better than everyone else, when actually anyone else in possession of the book (assuming he or she could read young Snape's handwriting) would be doing just as well. To me it appears that the only reason he doesn't give credit is because he's scared of it being thought of as cheating causing the book (and the compliments) to be taken away from him. He seems to consider it enough of an unfair advantage to want to keep it a secret.