I don't need to know ahead of time how much money they have) Same thing with time - if they want the business bad enough, they will find the time. If they don't they won't. So time doesn't matter. Anyone can come up with 12 hours (even if they tell you they can't). Anyone can come up with $2000 (even if they tell you they can't) But... when you ask about the 3 things - someone will usually tell you he doesn't have the money if he doesn't. So that flushes out the money issue most of the time.
Of course, whatever the other responses are, you will find out if that person is a good match for you. I got to where I could screen these so well that the Asia Email List average person I spoke with converted to a client 44% of the time. That's almost half. That saves time in my life. And it will in yours too, if you work on and master this concept of qualification. Here's the thing - that question could probably be asked about a lot of different "tasks" online. Because it's not just your email marketing that isn't working.
You have traffic channels. They aren't bringing you enough traffic. You look at each one, and something is wrong with each. Then someone comes to your site and they don't engage. So your landing page isn't working. Then someone does join your list, and they are supposed to get a series of automated emails from you. But the emails you send aren't just right for that one person.