Investors pay for the observation, not the evaluation. Whether the numbers work is their job, and most of them would rather you didn't guess, because a bird dog who prescreens on price tends to throw away the houses that were actually worth calling.
What makes a lead worth paying for is specificity. The full street address with the number visible in your photo. The date you saw it. What you actually observed rather than what you concluded, so "mail piled in the box, grass past the window sill, no vehicle" instead of "abandoned". Whether it looks occupied. And ideally the owner's name from the county's property records, which are free to search in most counties, though about a dozen states don't publish sale prices at all, so don't be surprised if that field is empty.
Being outside the industry is an advantage here. You cover ground on a schedule and you see the same block enough to notice change, and change is what investors are hunting.
One thing to be careful about: don't tell an owner you can buy their house or that you know someone who'll pay a certain price. Passing information is the whole role, and once you start discussing terms with an owner you're into activity that licensing statutes may cover, with the trigger written differently in each state. If you find yourself in that conversation, take the phone number and hand it off.
