Why must he ask that? Because it looks wrong. And is not accompanied by a comment warning that, though it looks wrong, it is intended.

Why does it look wrong? How does it look wrong?

Since you ask that question, I assume you haven't any experience maintaining large legacy code bases, with minimal test coverage, where the original authors have long since left the company.

Ugh, don't take this the wrong way, but that sounds like pure sundialsvc4ism

If code is that bad, how can you trust when they wrote  $_ //= '' for values %number_of_immortal_perl_monks they really meant to write that? After all it has no comment explaining even though it looks correct, we didn't make a mistake, we understood it for real to be correct, for really real this time

How can I learn when code "looks wrong"? I want to learn from you , can you teach me?

All three are equally clear at a glance (I glanced at them, equally clear, no headache)
Yet you did not notice the difference between "immoral" and "immortal"?

I did notice it, your first example was also a typo, and like I already said, perl will notice, perl is very good at catching typos