I have encountered versions of this scam in Central America, Mexico, the Caribbean, and numerous places in South East Asia. It functions in a similar fashion but there is always one common theme and unfortunately they prey on people's kindness. I actually found out about this scam by way of being a victim of it when I was first traveling in Asia, but saw versions of it all over the planet. I haven't been everywhere, but I presume that there is some variation of it everywhere.
It starts with a "parent" and their child
No one would suspect that someone would bring their child along on a ruse to rip off tourists would they? Certainly they would want to instill their children with better morals than theft, right? Well after being done over by this scam myself and talking to locals about it in other parts of the world I have found out that these kids are normally not related to the person but they rather will "rent" the kid for the day and while the kid does know what is going on, he or she is not an active part of the operation.
The parent and child will be hanging out at a tourist location and will be taking photos, probably pretending to take them, and then will approach you to ask if you will take a picture of him (it's always been men in my experience) and his kid. Because you are not the devil of course you oblige and afterwards he will ask you to take another one and then thank you. At this point he fires up a conversation with you with the usual small talk about where you are from etc and I gotta give it to these guys, they have done their homework because they normally know quite a lot about various locations around the globe.
The gracious stranger wants to reward your kindness
Small talk out of the way he will ask if you would like to join him for a drink at a nearby cafe where he "thanks" you for helping him to practice his English by buying you a beer. You have the beer, thinking how wonderful it is that you met this really nice resident of the community that is just out for the weekend with his kid enjoying the same things that you are. He will offer you "insider tips" about places that you must visit while you are there and in the two situations that I personally encountered (got ripped off at one of them) you feel as though this person is genuine. They are very good at what they do.
The San Filipe fort in Puerto Plata is where I encountered this scam the 2nd time, but I was already familiar with it by then
After they have instilled you with a sense of trust about this generous person that paid for your drinks (I don't think they actually pay, i think the shop is in on it as well) he invites you to come to dinner nearby with him and his son. Now that he has you feeling indebted to him and probably feeling a bit guilty for accepting this person's generosity, you agree to go and this is where the scam begins.
The move to a restaurant
The place normally has no menu in English or at least they are pretending as if they don't have one so your "guide" orders for the group.
You have a decent meal and then the kid will start tugging on Papa's shirt about needing to use the restroom, Papa and fake child disappear into the back of the restaurant never to return to the table, sticking you with the bill.
Of course since the menu had no prices on it you were not prepared for the dramatically overpriced food that you just consumed and you are in a bad situation. You don't really have much choice but to pay the bill because if you do get the police involved they are probably in on the scam as well and have an arrangement with the restaurant.
When I got done over by this in the past in Asia, I just paid the bill and accepted my fate and learned from it, but the internet is awash with stories of people that refused to pay and then nearly got arrested for their troubles. They have you dead to rights because in my situation where I did get scammed the owner actually DID have a menu that magically materialized once I protested that had the prices that were on my bill. It was pointless to protest.
Thankfully it wasn't a huge scam, just like $80 or so but a lot more than a small dinner should cost in a developing country.
When I encountered this same scam on the other side of the planet I decided to have some fun with the scammer and waste his time so he couldn't do it to someone else. I never went to the restaurant with him and told him at the first stage at the cafe that I had to get going and this is where his friendly demeanor disappeared and he demanded that I pay him for the beers. I agreed to pay what I already knew 2 bottles of beer cost but no more and walked away. He was shouting at me in English as I politely waved goodbye to him. I am not a small person at 180cm and 90kg and was traveling with a semi-professional kickboxer, so I was not afraid of any sort of physical confrontation in that instance. However, for someone smaller than me I think that physical intimidation would likely be the next step.
It is unfortunate but I think to be safe that it is probably a good idea when you meet a stranger with their kid at a tourist attraction it is probably a better idea to just tell them that you are not interested in going to the cafe in the first place or if you want to toy with them, YOU choose the cafe and you'll see how quickly he and his fake child immediately lose interest in having a drink with you.