Okay, guys, I'm just going to write some tips here to help avoid being scammed in the future:
1. Whoever has joined more recently or has less posts or has like none of their information filled out should let their villager be asked to move first. If they refuse, then look for someone else. While I know there could be a chance that the person's village is full, it's better to be safe than sorry. Exceptions for this are in #4! Please look at that too.
Similarly, if they need to drop off money/items, have them do that first or in a more fair way, half before and half after. You can follow them into the train station to see if they are talking to Porter before giving everything and if they are, just hit the Wifi switch. You don't lose your villager then and the only one who gets screwed over is the person who tried to scam you.
2. Constantly keep your inventory up if you are the one dropping things off. This keeps the seller from having a friend come over to save the game with half your items on the ground or something. If the person keeps coming, ask the seller to close the gate.
Heck, ask the seller to close the gate in the first place and follow them to see. Make the trade as safe as possible for both parties involved.
3. Check your map IMMEDIATELY to see if the villager is even in the town. If not? Leave.
4. If the user has been here for a while, CHECK THEIR FEEDBACK. If they have any questionable stuff, ask them to let you pick up from them first even if they have been around longer. That is PERFECTLY ACCEPTABLE.
But most of all, take screenshots. With Miiverse, you can literally just press the Home button when on the map, open up Miiverse, and make a post there and link us here. I would love to see more done about scamming, but it becomes a he said-she said thing and makes it really hard to to figure out who is telling the truth.
I know it's a bit harder when it's something like "this person didn't come to my town" unless you have messages specifically of scamming, but more often than not, I've seen those tend to be people who joined more recently.
And I'd like to just put a big disclaimer that says no, this will not stop all scams. I personally have been scammed out of something of mine in real life and money due to someone who acted trustworthy in the community and then just vanished from existence. There ARE people who will build up trust and join early and make friends and get these nice post counts and completely screw you over and it's awful and they obviously don't care considering how much backstabbing that is. That's what the other options are for though--there are ways to still prevent it.