Two fabrications made it into a recent client build and survived several review passes. Not through malice: "a decade in" her field was written as placeholder filler when the truth was five to six years, and three plausible speaking engagements were invented as scaffolding. All of it read right, which is exactly why it survived. Plausible scaffolding is indistinguishable from fact once it is in the file.
The rule that came out of it: if you cannot name the source, do not write the claim. And mark placeholders in a way that is impossible to ship, a comment reading UNEVIDENCED beside the value, never a plausible value on its own.
The subtler lessons are about how copy goes stale. Durations rot: "sixteen years" needs editing every January and silently goes wrong when nobody does it, which is the exact mechanism that let the fabricated decade survive. "Since 2010" is true forever. Tense is a factual claim too: "chairs" versus "has chaired" is the difference between a current and a former role, and anyone checking will spot it. Even prepositions carry claims. Spoken for an organisation means represented them. Spoken at means addressed them.
The commercial insight underneath: three evidenced claims beat six where half are padding. A reader who spots one unverifiable row starts doubting the verified ones next to it. Credibility is not additive. One weak claim taxes every strong one on the page.
This applies far beyond client sites. Every claim on this site follows the same rule, which is why the proof line on the homepage says two apps and not a vaguer, grander sentence.