You can always ask to see the realtors' license when you meet them. Here in New Jersey you can look us up on line on the Department of Banking and Insurance's website. In New York you can look them up here: https://appsext7.dos.ny.gov/nydos/selSearchType.do
In general, when renting, NEVER wire money anywhere. Insist on meeting the owner, or their licensed realtor, face to face and pay using certified or bank checks. Check the property tax records to be sure the person you meet actually owns the property. Be especially careful if you are using craigs list, as much as the administrators there try, they are frequently used to con artists. And if someone says they were recently transferred to some foreign country for their job, or because they are missionaries of some sort, and please fill out this application then wire the money to some bank account in another country, just run as fast as you can in the opposite direction! And, if it seems too good to be true, it probably is, be very, very cautious.