Ask a person in the street how they know politicians are lying and, more likely than not, they’ll reply: “Because their lips are moving".
Unfair? Sure. Politicians are mostly honourable people. So journalists have to take a more nuanced approach; we report that politicians “mis-speak”, they “over-promise” or, in Winston Churchill’s words, use “terminological inexactitudes”. Now, journalists are being called out on these overly generous circumlocutions. If it’s a lie, social media demands it be called one.