Wayne is the Poster Boy for the Dark Side of effective marketing: he gets lots and lots of leads, but not many of them are qualified. His % of qualified is probably at least as high as ours, but his volume is much higher, so he has a much bigger, more obvious version of the problem that we all have. He can essentially paint the problem and solution with broad strokes and bold colors, which does help the rest of us understand how we should deal with our own situations.
The Parieto Rule applies here, except it is more in the range 95:5, chaff:wheat. The ONLY way to separate them is to offer the opportunity to pay first. In the case of an off-plan 3.71 user where you are ROR, they will NOT pay you anything unless the call is essentially triggered by a change of executive management. Even then, they must pay something, even if it's just for an Initial Assessment (remote access, you define the timing, and price >=$1200) to see how much trouble they are in. If you want, you can offer that 1/2 of the fee will applied to the final proposal. An Annual Agreement is an even better thing to require.
Make the offer in email after a brief discussion on the phone, and don't bother to follow up. They know where you live, and you must underscore the sense that you have plenty to do without them. In a way, this is a virtual-world version of ""Wayne's Bathroom Test"" which tests whether the ownership respects its employees and vendors.