What makes the difference? How can I tell?
Can a mural be unofficial? Therefor not eligible
Is a banksy graffiti or art?
There are artists/graffiti-ists who create art pieces/graffiti/murals that are on official walls or commercially commissioned but who also create them unofficially in other places. Does it become graffiti when unofficial…Even when of high quality?
What? 
Now discuss
A good question.
A mural in my opinion is something that exists with the agreement of the property owner (either private or public) and is permanent. Permanance can often be established through StreetView, permission can be harder to track down but often there is a new story or website that talks about the mural.
Graffiti is typically temporary and is not created with the permission of the property owner. Some can be elaborate, but if it is without permission it often gets removed.
In between is graffiti applied without permission but which has become (almost) permanent. For example, this graffiti (it would never be an eligible wayspot) was very well known by people around the London area.
(h/t https://londonist.com/london/best-of-london/give-peas-a-chance-london-s-strangest-landmark)
So establish permanence + permission and you have a potential wayspot.
Not the best example, tbh.
Well, he doesn’t get permission when creating many of his pieces, and many now aren’t permanent, as vandals have stolen some of them. There was one at the London Zoo that he put on a garage door. The zoo removed it and replaced it with a replica, as they were worried that the door would be stolen. The replica could be considered permanent, as long as it’s noted as such.
There are also other examples of his art being stolen, to be sold on the black market some believe, or just covered up soon after being put up. So, for Banksy, there’s an issue with both permeance and permission, as he has not gotten the permission to post his art, and it may not stay up for long, which he is completely aware of (he just wants it to be seen for a short period of time and images of it be circulated).
Now, he has been commissioned for different art pieces, but it’s rare with him.
What is art, anyway?
I have a different take than the strictest views from the forum.
I think about it like this. If I were the building owner, would I be angry that this “art” is on my wall, and would I immediately make plans to remove it and repair the damage? Or would I be okay with it, happy even? So maybe it wasn’t planned, but if I’m not going to remove it, maybe that’s okay too.
There is a local artist called Peachy whose work pops up everywhere, and it stays. I haven’t seen anything removed so far of theirs, even though I am not sure if they ask permission all the time. Like Banksy, they remain anonymous. Their work is easily accepted by the wayfarer community with no proof of permission provided.
Scribbles and tags are not the same thing. Almost nobody thinks those are artistic.
