Yeah, admins should be strict when needed, but the rest of the time be fun. A lot of forums have such strict rules, and the administrators or staff always have to be so 'perfect' using perfect grammar, long posts, ect. when they could easily be driving their own members away. I've had sites with staff that did that, and I'll never do it again, they ended up total failures.
There are times when you do need to be serious and strict but for a majority of the time you should be "fun" and interact with other members and have a laugh. Some forums feel intimidated and uncomfortable when admins never post and only post when they warn a member or something and when the admin is too serious.