Every form submission, in the person's own words, with where they came from. Label each one so tests are judged on good leads, not just more leads.
“Got your name from a neighbour. Can someone come look at basement windows this week? Evenings work best.”
“Need a quote for a new front door. House in Royal Oak, hoping to get it done in the next few weeks.”
The AI labels every lead. “Needs review” means it was unsure, so a person decides; anyone can change any label. The AI reads the answers only, never names, emails or phone numbers.