Don’t make a listing appointment seem like a big deal.
You’re just asking to look at their house. You’re not asking them for money, you’re not asking them for a listing. This is just an appointment to look at their house.
Saying something along the lines of, “Hey, your house didn’t sell, I’m a realtor, I may have some good ideas. Can I stop by sometime and just take a look at it, and see if I can give you any good ideas?” And people say, “Yeah. What the heck? That sounds great.”