Porn stars, or any celebrity for that matter, are regular people. They need to take a shit just like anyone else; and seriously, it's pretty damn impossible to look glamorous while taking a dump.
Of course they have friends and hang-out, but how they react to being recognized in public shows how professional they are. Some people go into "star mode" or the stage persona only situationaly and prefer to lead the rest of their lives in anonymity. You will be shocked at the difference if you ever meet them in performance/schmoozing mode versus going to the grocery store mode. Other people are always in character (or want to be), and if this is the case, be afraid and slowly back away. And even other celebrities are just able to deal with their public and private personae in a healthy manner and can switch back and forth seamlessly and simultaneously without loosing a core identity. It is your job as a fan to control yourself and not put them in a scary situation where they feel threatened and have to call the bodyguard. Let's be real here, everyone, I mean everyone sometimes has a bad day. If that is the case, leave the person fucking alone. The rejection is not personal and has nothing to do with you; just bad timing on your part. And hey, if they are prima donnas and treat their fans like shit all the time, they won't have any fans left. And honestly, you can't be a star if you have no fans.