A lot of people lie (I'll say people because most everyone does it at one time or another) because they are scared of the other persons reaction.\
It comes down to the lesser of two evils in some peoples mind, and lying to save face, without consequence is often times the winner. Does that mean it is right or correct? No.
People may lie to try and play the system of honesty, but you know what? All the men that lied to you, are they in your life directly now? (If not then I guess lying didn't work out so well for them)
There could be many reasons to lie, too many to name actually as it differs per person. I used to lie a lot as a child, but I grew out of it. If you want the sweeter things in life, and without tainting a relationship, then you must be honest. That means about everything.
It could also boil down to how a person was raised. The golden rule in my family was honesty, and although I didn't realize it at the time, being honest gives much greater rewards than dishonesty.
All in all it sums up to how much you decide you will take. (How many lies you will accept) If you decide not to take liars anymore, then don't get vengeful, mean spirited or nasty, just walk out of their life and don't look back.
Although this has been a giant tangent, I hope you can understand at least a little bit of this man's views.