Welp, I managed to get the filter free of smudges. This is a good thing. I decided that testing was in order to make sure. So I shot my resolution chart to take a look. One shot with the polarizer, and one without. Over all, my cheap ($50) polarizer seems to reduce contrast over-all, and drastically fuzz out in the corners. I’m going to make another pass at the filter will a little distilled water and detergent, but I think it may be time to upgrade to a better filter.