Here's my spiel;
After introductions and pleasantries, I get down to it lest they think I'm there for religious or nefarious reasons.
My offer is this:
Do you want to see what I find ?
If you like that, I'll do my research and give you that and the pics of what I find. (or what they may be interested in)
If I find something that would be important to your family and you want it, it's yours.
If I find anything really valuable like a brick of gold, I'll split it with you.
Otherwise, I'll fill all my holes with the plugs I took out to save your grass, remove all the trash I find, and If you have company here (lots of cars)
I'll pass by until another day, and if there's ever any reason you'd rather I not be there that day, please just say,
I don't mind, and I'll be gone until it's OK for you.
This way, you automatically answer most of the questions they may have then or esp. later when they have a chance to think about it.
I also let them know I will be there more than once. Some people think it's just an hour's visit.
If that's all they give me, I'll take it. But if you've told them in advance, relationships will be better, and they will be
more likely to turn you on to relatives, neighbors, and friends. (which they will)