I'm not upset that you lied to me, I'm upset that from now on I can't believe you. - Friedrich Nietzsche
The worst lies are the lies we tell ourselves. We live in denial of what we do, even what we think. We do this because we’re afraid. We fear we will not find love, and when we find it we fear we’ll lose it. We fear that if we do not have love we will be unhappy. - Richard Bach
Sometimes men lie because they do not see the need to cause uneccesary hurt and sometimes because they fear the outcome of the truth.
I don't think we have to brutally open and honest all the time eg "Hows was your day today dear?" - "Great, I shagged my secretary and she's a real goer!". Yet lying or deceiving with a "I never had sex with that woman!" is equally not an option. Personally I try to shift the subject or answer truthfully but leave a different impression - "Don't ask me. You don't want to know!"