I just take the disc from the spindle, into the liteon burner and burn away. I didn't notice any dirt or such on the bottom of the disc. I play it on a ps2 for a while and then I kprobe it. After I'm done kprobing, I take out the disc and see a some sort of debris, really small on the bottom. I wipe it off and I see a small spot in that part of the cd dye right under where the debris was. The spot is dark compared to the lighter parts that got written data. Should I worry about that? I kprobed the whole dvd and the highest PI I got was 120 and average of 55.