Thick Face : The art of hiding your inner self, plans and aims from others around you.
Black Heart : The ambition to achieve your goals with all means and with total disregard for the consequences for those around you.
Using a "Western" set of references the philosophy of Thick Face Black Heart will have a purely negative meaning. Thick Face will be regarded as insincere and secretive and Black Heart will be considered devious and destructive.
Whereas it is possible to use Thick Face Black Heart in a purely negative manner in essence it does not have a moral dimension.
From an "Oriental" point of view Thick Face might merely be a cautious attitude necessary in the light of adverse conditions. Black Heart can be considered a justified course of action since everybody has the right to pursue his/her goals in life. Especially in case someone else's goals are directly opposed to one's own.
Thick Face Black Heart is neither negative nor positive. It can be used in either extreme manner but is normally considered to represent cautious behaviour and smart (business) tactics. "Not showing all your cards" and "striking while the iron is hot" could be an accurate translation and as such understood by all.
Openess and directness are valued "Western" concepts. According to "Oriental" cultural perception these concepts can not only be merely impolite but also downright dangerous, for both interacting parties. Thick Face Black Heart is originally a Chinese philosophy but all Southeast-Asian cultures have adopted these principles many centuries ago.