I’ve had few games where i’ve kept malkovich logs when my opponent has asked me to, and i think it’s a great tool for correspondence teaching games.
Good thing: it’s lot easier to leave a comment in the middle of playing, instead having to remember what i wanted to say in a review after the game.
Bad things: it’s really hard to make a positive comment on my opponents move, because it’s mostly the mistakes that can be spotted right after they are played. This tends to make malkolog just a pile trash talk and negativity of "what on earth is black thinking, doesn’t he see it’s a ladder…"
Another downside of malkologs is that they are visible for other player only after a game, and when i’m playing a corr. teaching game i’d rather give that feedback directly to my opponent, so they can undo and find some other move.
Few, somewhat old, malkogames: Levvo's Corner and List Your Malkovich Game Here