I think it's up to the host. I always answer the door naked if I'm expecting a nudist. If they want they can drive to my places naked and come naked to the back door. If I'm visiting a nudist I'll ask. It's their neighbourhood. If they are concerned I'm dressed if not I'm naked.
When nudists meet dressed there is always that problem of breaking the ice - who undresses first. If I'm the guest I might hesitate for a while. Otherwise it's off with the kit. Who cares if I'm the only one naked. It happens quite often.
I love being naked around clothed people. As long as everyone's comfortable, right?
Yes. Almost always I will drop trou even if I am the only one and I enjoy it immensely. Was surprised last Saturday at a CO party that I didn't, and I think that it was because there were some people there who were uncomfortable, or who might make it a source of cluck cluck gossip. Vibe just wasnt right. Perfect weather, sort of disappointed in myself but I guess I navigated an evening pretty well with people I don't know anyway.