Polarizing Filter vs Natural Density

I was in a photo store the other day and the owner told me a better way to get a Natural Density filter effect was to take 2 Polarizing Filter and rotate one against the other to get the Density you want. The more you turn the one Polarizing Filter against the other the darker it gets. He also told me that in the long run you save on having to buy a 2, 4, 6 etc. Natural Density Filter.
Has anyone ever tried these combo of 2 Polarizing Filter together?

I do it all the time. (fall shots with my varicolor polarizers and regular polarizers....and sometimes with two regular polarizers for fun)

two catches:
A) cheap polarizers (one should be linear instead of circular) can cause a dramatic and sometimes uneven color cast (usually purple).
B) two layers of glass = two times the number of surfaces between your lens and your subject... twice the chances of dust, flare, and image quality loss etc...

so buy good filters and really get the graduated nd's at least...

I think you mean neutral density. Using 2 polarizers in this way will cost you about 2 f-stops, if not more.

What exactly is the point? Why not just underexpose if you want to lower the overall brightness of the scene?

shallower dof and or slower shutterspeeds....

I often need both a polarizer and a ndgrad for outdoor portraits...
ie getting shallower dof and a slow enough shutter speed for flash in a park setting...

Thanks Don.

U R Welcome!
another good use for two polarizers is to put one on your flash and the other on your lens...
then you can "Dial out" glare off reflective surfaces (not chrome or mirrors) or oily skin and esp dark colored skin.