Well, I try. Having ideas is like any other skill, you have to keep practicing.
I'd suspect they always have some charge. But try it!
Just a big resistor to ground and a decent fet opamp should work, with maybe some protection diodes. As the drop squishes into the pan, a zot of charge will be deposited. The nice Vaisalia paper has a graph of drop diameter vs velocity, so the charge zots should be in the millisecond, maybe less, sort of range, assuming the water's not very conductive. If there's a lot of charge, you might even get a spark at contact; I have no idea what the incoming voltages or the signs might be.
This would be fun.
John