Having had sex with well over 1,000 of those Asians, I have never once found one to have worst breath that Americans (unless they are smokers and then no matter where they are from it is disgusting).
Thais take care of their body and are the cleanest people I have met. They don't take care of their teeth as often as most don't know to go to the dentist every year. But, they still have pretty teeth.