Quote 1
"I have twenty people begging for this apartment," Barney Northrup said, lying through his buckteeth. "Take it or leave it." (1.30)
Well, Barney is actually lying on several levels. He tells each tenant that twenty other folks are "begging" for whatever apartment he's showing, but we know that's impossible – only six letters were sent out advertising the place. He has the same spiel for each tenant and must be doing something right, because by the time his work is done, he's rented the building exactly as he wanted to. As we also know at this point, though, Barney's lying by just virtue of pretending to be someone named Barney.
Quote 2
"The front apartments are taken," Barney Northrup said. "Besides, the rent's too steep for a secretary's salary. Believe me, you get the same luxuries here at a third of the price." (1.16)
Barney's sales pitch preys on ideas many of us share—get the expensive benefits the wealthy enjoy without having to pay as much for them. This combination of apparent high class and bargain pricing works extremely well, and it doesn't hurt that Barney seems to have an uncanny understanding of each potential tenant's financial status.