Only 20 percent of the ATMs are safe in Thailand the rest are the old model and can not be trusted. The skimming has become such a big problem now in Thailand that The Bank of Thailand has ordered all banks to change to the new version of ATM.
With the old model a person can insert a card inside the ATM and read your information and with a small cam they can see your code.
If you travel to Thailand you might not know that you been scammed before you come home.
If possible please use the ATM in a bank or a shopping mall since they have 24/7 surveillance.