Here's a comparison of 2 filters. They're UV filters, not polarizing filters, but the comparison here is between coatings so it's still relevant. On the left is a high end Hoya HD UV filter. On the right is a super cheap Targus "multi coated" filter that I bought at WalMart (UV + CPL costs all of $16 USD). Both filters are angled so they reflect the exact same light bulb, a 40 watt CFL in my home office. Both filters are sitting on a white towel.
Now remember, the coating on a filter i supposed to help PREVENT reflections. The idea is to allow more light through the glass by reflecting less of it. So the brighter the reflection, the crappier the coating. I think the picture speaks for itself. It's worth noting that the effect is even more dramatic when I'm holding the filters away from a surface. Having the towel right behind the filters is creating sort of a "mirror" effect. But I have yet to figure out how to precisely aim both filters to simultaneously reflect the light while taking a picture of them.
Keep in mind, even the crappy Targus filter is marketed as "multi coated". An uncoated one would be worse. All that reflected light is light that doesn't get into the camera when you need it.