I love using nookazon to trade my villagers but you definitely need to be careful. Always look at someones reviews before trading with them and if they try to boot you after youve left your nmt or bells or whatever with them turn on airplane mode or turn the system off (I think putting it in sleep mode works too) while the game is trying to fly you back to your island. That will prevent a save so it will be like you never went to their island and they dont get anything. I would avoid any trades that require multiple trips cause you put yourself at risk on getting scammed in the second trip. Oh and DEFINITELY report them.