Your post reminded me that,

"Self-Service Linux: Mastering the Art of Problem Determination" from Prentice Hall is a nice book that I can heartily recommend.

http://www.phptr.com/title/013147751X

"Art of Problem Determination" part is better than "Linux" part in this book, in my opinion. I'm sure you already know all the stuffs in this book, but it's great to see these "implicit knowledge" of debugging described in the prose.

Prentice Hall offers first 40 pages of the book in PDF format, which deals with methodology of debugging. "Investigation log", which is essentially equivalent to your "bug scribble" I think, is described from page 14.

A sample paragraph, in case you don't want to bother downloading it. :)

"An investigation log is a history of what has been done so far for the investigation of a problem. It should include theories about what the problem could be or what avenues of investigation might help to narrow down the problem. As much as possible, it should contain real evidence that helps lead you to the current point of investigation. Be very careful about making assumptions, and be very careful about qualitative proofs (proofs that contain no concrete evidence)."

Then a sample investigation log follows, which is in turn annotated.

-- Seo Sanghyeon