I would like to give my opinion about this since I live here near Petra and I hear many stories... So based on these stories that I know, I can tell you the truth.
Yes, the tourist police in Petra is present and actually quite effective because if a foreign tourist complains about a local, the local accused person goes more or less straight to jail without too much questions asked.
So if you ever get into SERIOUS problems, you should report to police.
About the rape story inside Small Petra, I cannot say if it is true or not 100%. I have not heard this story. It could be partially true but I doubt about being drugged and being raped by "10 bedouins" part.
Anyway, the truth is that we consider mostly Petra to be a very safe place with many good hearted Bedouin people living it. The chances of you getting into possible dangerous situations mostly depends on your decisions made by your common senses.
Dinner parties inside Small Petra is very common here (we do it all the time with or without tourists) and I cannot say that it is totally a dangerous activities to do.
But here in Petra, one truth is that there are quite many young (age 18-30) "homeless" bedouin guys, very jaded and infected by too much influence by thewestern tourism these days, who are very known to be alcoholic, irrespectful of their own religious duties, and also, majorly known as "romantic gigolos" who always hussle every single women they see, in the most sweet credible manners (I mean "sweet" until you fall for it). They litterally ONLY THINK ABOUT SEX ALL DAY LONG.
They invite you for a beautiful sunset and million stars at night... or to have a party in small Petra or in the desert (with alcohol it could be more dangerous because when these "homeless" guys get drunk they could get VERY aggressive and horney)
With their cheesy romantic words or sudden invitation for marriage, they make you fall in love with you, then they will have sex with you, then try to suck up money from you pretending to sound poor and in need of money for the family. (typical way to do this is by saying something like: "my donkey died and therefore I cannot work")
Anyway, the point that I am trying to make is that, when you travel anywhere, you should be open minded about many things, talk to local people, try things that you don't do usually back at home...etc.
BUT HERE INSIDE PETRA, ESPECIALLY IF YOU ARE A WOMAN TRAVELLER ALONE OR WITH ANOTHER FRIEND, WATCH OUT FOR THOSE WHO ARE TOO SWEET WITH YOU OR WHO WANT TO TALK ABOUT LOVE OR SEX.
Last thing: I want to say that this "homeless" culture has NOTHING to do with the real bedouin culture. The real bedouins are good, respetful and hospitable people who will make your visit wonderful and unforgettable.
There is absolutely no doubt about it... so PLEASE TRY TO SAVE YOURSELVES AND TIME FROM THESE "HOMELESS".