For people who are not sincere, honest or trusthworthy, there is a “time-limit” of their “deception”. Even if the person deceived is the most naive person in the world, she/he can trace back and understand the real intention of the deceiver. This is called retrospecive thinking and it is best described by Abraham Lincoln:
“You can fool all the people some of the time, and some of the people all the time, but you cannot fool all the people all the time” Abraham Lincoln
In business or private life, if someone is not honest, in the short or long run that person always pays the price of not being honest.