Young people getting into sales are still trained to hammer people who tell them they are not interested. Didn't that ethos disappear shortly after the atmosphere was forming and the Earth cooled?
It didn't. And, as companies get more desperate with slumping sales, many are telling their salesforce "not to take no for an answer". It's pathetic.
I have recently been VERY near three Fortune 500 companies who still teach this. Just three days ago, I had an experience with a mobile phone carrier who still thinks this constitutes clever tactics. (I won't say their name but it rhymes with ""Flint Bextel").
They don't call it "hammering", of course. It's called "overcoming objections". Many mentors/trainers still ascribe to the "you must hear five(5) no's" before you should stop. I'm not kidding. So why is it, exactly, the average consumer/buyer loathes salespeople?
By all means, if you're working with a customer who you know and have at least a business relationship with, probe aplenty. You've earned that right. They're so busy, half the time you know more about their needs than they do. But even if they adore you, customers often will reflexively say "no" before they even understand what they are saying 'no' to.
If you are talking to strangers..prospecting, it's different.
If you're forced to make cold-call telemarketing calls, don't do this. Not only will you fail miserably, you'll feel pretty lousy about yourself and what you do for a living. Cold calling can actually work...if you've got some SERIOUS phone skills and the people on the other line are in the market (or will be soon).