permalinks to posts

how do these work exactly?
when i permalink a post when i'm logged in and then post it in a thread then it works while i'm logged in, but goes elsewhere when i'm not logged in.

came up in the werewolf gameplay thread, about post 1656

Permalinks don't work if you have difference posts per page from what I remember.

You're better off either stating the number of the post or clicking the number and linking to that new page