How do I tell a good shortcut from bad tech debt?

You are adding to the mess because you cannot yet tell a fair shortcut from a real trap, and honestly, that judgment is one of the last things to arrive. Everyone writes debt they do not recognize at first. Naming the gap the way you just did is actually the first real step out of it. Here is a rough compass. A good shortcut is one you could undo cheaply later, that is contained, that you understand while you take it. A trap is one that spreads, that others will build on top of, that you are taking because you do not fully understand the right way. The difference is not speed. It is whether the future stays open or quietly closes. So next time you reach for a shortcut, ask one question: if I need to undo this in six months, how hard will it be? If the honest answer is easy and contained, take it. If it is hard, or you are not sure, slow down or ask someone. You build this instinct by asking that question again and again until it starts answering itself.