I guess we all know sales people who would rather lie than even admit a passing acquaintance with the truth. From the gal who claims her product can do things it can't, to the guy I know who continues to lie about his marital status just to get his "hot" customers between the sheets, and/or onto the balance sheet. (The same guy claims commission on purchase orders that don't exist, and adds notches to his belt for conquests he's never had.)
People lie because they're embarrassed by, or afraid of the truth. Add one more reason for sales people to lie: the truth they fear is that they're lousy sales people.
Sell the truth. It takes more talent, it takes a little longer, you lose some sales until you realize that selling to the wrong customer may be part of the problem. Once you focus your efforts, prepare, build your product and market knowledge, the truth will set your fee; nice and high.
Sell the truth. Watch this rant: http://youtu.be/sr3NTmv5sIk