in reply to
How do you critique another person's code?
Thanks for sharing that in such detail. Painful but entertaining, particularly the comments. And always worthwhile: a lesson in folly is worth two in wisdom as the man said.
As to tackling the feedback, my only observation wd be be as specific as possible. I think people who do a lot of programming know that abstract, aesthetic issues in code really do matter - they are very good pointers not just to little niggles but to systemic disasters that will happen. But for people who don't think that way, the most persuasive criticisms are, IMHO, ones of the form "This line of code would, under such-and-such circumstances, give rise to this specific bad thing happening".
Having said that, Draino in the chap's coffee is probably a good fallback plan. Good luck!
§ George Sherston