The spammers don't actually keep tabs on things like this, nor share them among competing spammers as you've suggested. That adds cost that they don't need to w

The spammers don't actually keep tabs on things like this, nor share them among competing spammers as you've suggested. That adds cost that they don't need to worry about since everything is automated anyway, and their calls are essentially free to them. You might piss off the "operator" you eventually got to speak to, but the best way they have to get back at you for it, is to just let you keep getting their calls. They call random numbers for certain areas, just as they use random semi-localized numbers for the recipient to see. You probably have an area or prefix that isn't all pumped up with spammers at the moment. But it's not because you're being clever with them (although that can indeed be fun).