Hua-hin, Pattaya, Chiang-Mai and Bangkok are most common target cities.
A Pattaya scam have already striked in Hua Hin. See http://www.pattayascam.com for details.
To avoid this scam ensure:

1. You can verify all the information provided
2. USe established business operators, e.g. Sunbelt Asia, Real-e-sate, etc.
3. Do not sign any contract with overseas companies without legal advice.