As much as I dislike more than almost anyone I know being disturbed by telemarketers
I have always told myself that most of these people are simply trying to
make a living with a tough and thankless job. I try to tell them quickly
but kindly, in a cheerful friendly way, that I am not in the market, that
I want to save their time because I know they're trying to make a living
and I wish them "good luck". This I find, is better than pretending
to be interested, raising their hopes unnecessarily and wasting their and
your time and patience.
you know someone so hard up they have to make ends meet by telemarketing,
give them some flowers. Anyone who has to wallow through that much rejection
every day needs some random kindness!