@Megan397,
Most i my guests are international, so not really to worry about. But the guests profile (verifications !), the reviews and the communication must be taken into good consideration wheter to accept or decline the booking request.
It is also good practice to ask some questions, like "what is the purpose of your stay", if you have doubts.
Scamming people are everywhere, just try to avoid them. I (lucky me) never came onto a scamming guest. If not a good feeling about a guest: better decline then taking a risk !
Hope this helps,
Emiel