In the local markets, counterfeits of everything imaginable are available. Meanwhile folks who have travelled to Cambodia claim fake US dollars are everywhere. The rumour is that they are printed by the government of China, so are of high quality. Add to that the fact that Thai banks will not exchange old US notes, even when in excellent condition, and there is much confusion over what is real and what is fake.
So, travellers beware when exchanging travellers’ cheques for dollars or for baht.
Yes, there are fake baht notes as well.