[coldtea]

All of these are debt. They only subjective part is how much of a debt they are.

But bad comments (even if it's just grammar) and misspelled variables are indeed part of debt. To see whether something is debt or not, imagine it piling up everywhere in the code.

What if 60% of variables in the code base had "incorrect capitalization"? What if most comments had the "wrong grammar"?

It would be more difficult to understand, refactor, and extend the program. Well, that's debt.

Debt can be negligible when it's like one dollar, but it can creep up and accumulate if we let it.

Also think of the "broken window" theory. Sloppy comments here, mistyped vars there, give a signal that "everything goes".

https://en.wikipedia.org/wiki/Broken_windows_theory