Ma Ying-jeou, the President of the Republic of China (Taiwan) examples for us a basic and important premise in the science and art of Body Language - that of "Norming" - or in other words, establishing a baseline behavior. One reliable signal of insincerity is speaking out of the side of the mouth, however when people do it continuously (which is relatively unusual or even rare) - it is part of their normal, everyday behavior - part of their baseline personality. It also has similarity to an expression of contempt and may also be a metric of anxiety - depending on the other nonverbals with which it is clustered. Thus, it would be inaccurate to use this particular tell as an "insincerity, lie or contempt detector". Of course, such an individual may still be insincere, lying or contemptuous, but we just cannot use this signal to detect these acts in these people.
Ma Ying-jeou speaks out of the right side of his mouth so often, this is undoubtedly part of his normal baseline behavior.