"Desperate" salesmen of "undesirable" real estate, as Wikipedia aptly describes both.
To a salesperson, or a person considering sales work, that "undesirable" is a key tool to overcome discomfort with the story: selling "desirable" goods and services is what makes selling good. So, the real reason for desperation in the story is that the wares to be sold are undesirable.
Now, a good salesperson’s career includes striving to get to sell good stuff, so maybe the real reason for that real reason is that salesmen here got stuck with "undesirable" wares to sell.
Interestingly, every salesman in the story looks better at conning – er, selling to – his peers, who presumably know better than that and better than prospective buyers about it, than to actual prospective buyers. This may be what drives the claustrophobic twist to the team’s desperation.