How to determine the truth?

Sometimes a Yes could be a No or a No could be a Yes. So when someone says a Yes or a No to you, would you be able to see the truth in them. 

The polices are the best profession who could sense the truth from those who are caught by them. On interrogation with the bad guys, police has their techniques to determine whether they are telling the truth. 

I learned from them. On interrogation with a gangster, police would ask many questions, when that gangster has only to reply either a Yes or a No. Nothing more. The first many questions asked, the police officer himself would know the answers. Questions like; Is your name Lee? Are you staying in KL? Are you working with ABC?  The gangster would reply with only the Yes or No, depending on the officer choices. Each of the Yes and No would be recorded in the officer very attentive ear. He has to sense and to listen to the pitches, tune and clarity of the Yes and the No. The vibration of each answer could determine the truth later. At the same time he seriously look deep into the gangster's eyes for his answer. Finally when he has gathered enough of confidence, officer would ask his key question. Answer me Yes or No, "Did you rape the lady?" Staring at him and carefully listen to the Yes or No, officer would be able to justify the truth from the bad or good guy.

Though I'm not a police, I'm glad I had mastered the skill from them. In selling I know whether my prospects and clients are telling the truth. With friends I know whether they are sincere with me. With little darling I know whether she is faithful with me. What I have got to do is just listen to their two words, Yes or No, Simple as that. 

Confusing proverb - "I love you and because I love you, I would sooner have you hate me for telling you the truth than adore me for telling you lies" - Pietro Aretino quotes.