I'm going to support the "frisbee philosophy" here.
If an area has a caching policy, great. I'm happy to follow the rules. If it doesn't and has open public access, I don't see any need to open a can of worms by asking permission.
Why? Because it is the job of administrators and managers to say "no" whenever they're confronted with something new, unknown, or different.
My motto is "easier to ask forgiveness than permission" and it's served me well for a long time.
Now, all that said, my primary concern is not the cache, or myself as cache owner but of the cache seeker. Am I endangering this person by having them seek a cache at any particular location? Are they trespassing? Will they look overly suspicious and thus be subject to landowner/police oversight?
It is my responsibility to take into account the surrounding land management rules that may apply to cache visitors. They are my "guests"
One thing I'll never understand is the inability of cachers to be discrete in seeking a cache EVEN WHEN the cache description clearly states that it has been placed surreptitiously.
On the one hand, this is a nod towards asking permission (then people wouldn't have to be so stealthy). On the other, it means that, in many instances, instead of a short lived cache, we'd have no cache at all.
Thoughts?