I'll bet the guy who wrote the 10 year old C++ code I am debugging for memory leaks thought it was obvious what he was thinking, when he wrote it. Alas, no documentation *at all*. A whole load of low level memory manipulation to fit into one can only presume was 640K of memory ... <sigh>.
Well you are debugging poorly written code. If the code you are reading is hard to understand, that's the code's problem. I stick to what I said: clean code doesn't need (and shouldn't have) comments. Why? Because clean code is ALWAYS understandable in it's own right.