Though some of you say there are unwritten rules, it's best that something is said just to avoid hard feelings. Whether you are the host or guest, it's best to mention, "How do we work this? Whatever you find you keep or shall we divvy up the finds unless it's a cache?" Also, be careful who you invite. Do you mind if they come back on their own or bring others without telling you? Out of respect for my friend, I've intentionally avoided a site that he previously showed me. Others have not and I know that doesn't sit very well with him.