Contrary (perhaps) to what many TeX people experience, much of the LaTeX that I have to untangle is not written by me. At elsevier Science we accept LaTeX files for more or less any of our 1200+ journals, and our production editors have to coerce the submissions into a standard form so that we can apply our journal-specific styles. Along the way, many problems can arise, and we hold in-house training sessions to discuss techniques for finding bugs in other people's LaTeX. These notes arise from those sessions, and are offered as a light-hearted reminder to LaTeX writers and editors alike about some of the ways the agony of using idiosyncratic system can be lessened. Following a felicitous parallel drawn by TUGboat reviewer of this article, think of this like those posters on the doctor's wall which you read while waiting to see the specialist. It is not a serious guide to TeX debugging, for which I am not qualified, and which would require a very large book indeed...