Yea, this is probably when [otherwise cautious] people are most susceptible to falling for these scams.

When applying for jobs, there is nothing more irritating than seeing a missed call, getting excited/anxious, and calling back...a #%*@^ telemarketer. On the flip side, I briefly forget that I am unemployed, since all I think about for the next 5 minutes is inflicting the most sadistic forms of torture on every telemarketer that has ever lived.

Seriously though, googling unknown numbers does help.