Try looking at an LCD screen with polarised glasses. If you can see it then rotate the screen or your glasses 90 degrees and it will disappear.
A good example of this is an iPad. I was in the right hand seat while my flying partner was P1 in our PA28. I took my new iPad up with me to try out a few of the moving map prodcts and to test the GPS reliability. I had my polarised sunglasses on and I seriously thought the iPad had broken on me. I switched it off / on, hard re-booted it and did everything I could to make it work. Then I took my polarised glasses off, and voila, iPad is working after all
. I must admit I never had any other issues. No depth issues, and things seems fine in low vis, in and and above cloud too.