Earlier quoted context omitted.
My opinion is that 'not thinking or understanding' the work shouldn't be labelled as technical debt. Technical debt should be a conscious decision about an implementation that needs to be revisited in the future, either for scalability, readability, extendibility etc concerns. Also, in that vein, not writing unit tests should not be considered technical debt, that is part of any implementation and should be factored…
If it is ‘debt’ you actually plan to pay it. Sometimes I’ve put off writing the unit test (in an area of the code that has been around for months or years w/ little or no testing.) and made a bug fix or small feature. I had a plan to revisit it when coming back to the same zone and did. I’ll justify it like this. If a system is not well-modularized for testing and there isn’t a precedent for mocking or similar method…
Exactly that, and it should be a decision to accrue it.