That is what code reviews are for.
Yes. As I said, you leave the figuring out for after you've left.
This "comments are for crappy code" idea isn't magical crap I make up the other day, it's fairly accepted idea these days in software engineering circles that comments are a crutch for poorly written code.
Here is a quote you can ponder if you like:
“The proper use of comments is to compensate for our failure to express yourself in code. Note that I used the word failure. I meant it. Comments are always failures.” --Robert Martin
Read the whole thing. Even he admits it isn't possible.
And while I applaud and encourage the "Agile is Pefection" concept, I'm adult enough to recognize that reality doesn't always work that way.