I've said this before: if you stay within the law in Thailand and avoid bargirls and others foreigners, you should be safe.
When meeting foreigners, be VERY cautious. Many or most of them are liars, crooks, scammers, perverts, mentally disturbed, psychopaths / sociopaths, drug addicts, etc.
Never believe what foreigners tell you. Play it cool. If the foreigner is telling you the truth about his current or former career, it'll become evident soon enough. Don't rush into new friendships or stupid business deals.
In almost all cases, avoid business deals with Thais. Keep yourself to yourself and you won't go wrong.
Be happy! Enjoy Thailand.