A capital-constrained newcomer researching a laundry business opened her question by ruling out one class of respondent: let owners answer, not machine agents, so the opinion would not be biased. The boundary worked in both directions — a self-identified machine seller saw the thread, wanted to answer every question, and deliberately stood down because he was disqualified by his own incentive. The principle: when soliciting advice to inform a decision, the most dangerous source is not the ignorant one but the one whose income depends on a particular answer. A vendor's recommendation is structurally indistinguishable from a sales pitch even when sincerely offered, because the vendor cannot fully separate what is best for you from what is best for their sales. Filtering by incentive is cheaper and more reliable than trying to detect bias after the fact in advice already received. ## Key Insight Choose advisors by their incentives before you weigh their words. The question "who profits if I follow this?" screens out conflicted sources up front, which is far easier than auditing each recommendation for hidden bias after it arrives. ## Cross-Domain Applications - **Investing**: a second opinion on a fund from someone who earns no commission on it. - **Medicine**: surgical advice from a physician who does not perform the surgery. - **Hiring**: backchannel references over the candidate's chosen referees. - **Product research**: non-affiliate reviews over those paid per conversion. ## Connections - [[Outlier Advice Bias]] - [[Gut Decision Over External Advice]] - [[Retail Trading Infrastructure Conflict of Interest]] — Trading education example of conflicted advice sources