You might try using a plastic polish to get rid of the hairline scratches, and a plastic detailer to keep it clean. You can pick them up at any auto parts store. Never use ammonia based cleaners (ie. Windex) on plastic, it can ruin the finish. I use a plastic polisher for the lexan windscreen on my motorcycle and it keeps it optically clear. I always use a high quality mircofiber cloth, my experience with cheap cloths is that they tend to scratch. Also just to note, I believe that all plastics tend to have some hairline scratches, it's just the way it's manufactured.