A 4-question gut-check before I bother with any peptide

Before I spend time (or money on bloodwork, or a clinician visit) looking into any compound, I run the same four questions, and most things fall out at step one: 1. What's the actual human evidence? Not "studies exist" — human, not just mice or a cell line. If the honest answer is "preclinical only," that's fine, but I want to know that going in. 2. What problem am I actually trying to solve, and is there a boring, well-evidenced answer first (sleep, training, diet, a real diagnosis)? 3. Could I tell if it worked? If there's no marker I can track and no way to separate it from placebo, my "results" are basically a story I'm telling myself. 4. What does the downside look like, and would I be comfortable explaining this choice to a doctor? I'm curious what's on your checklist — what's the question that kills most ideas for you before they start?