From the Everything I Needed To Know I Learned In Kindergarten Department:
Netflix has over two million subscribers. None of us wants to receive a damaged DVD, or one with fingerprints or scratches on it. Someone else had it before you did, and someone else will get it after you. 99% of the discs at your local distribution center go to someone else the next day. Please use care in handling your DVDs from Netflix. Here are a few tips:
Handle a DVD more carefully than a CD.
Do not bend or twist discs.
Handle discs only from the edges and the center hole.
Do not touch the disc surface.
Don’t stack discs.
Make sure the disc is properly seated in the tray before closing the door.
Single-sided discs should be inserted with the titles and artwork facing up.
Always store the disc in its sleeve.
Keep discs away from extreme heat or direct sunlight (don't leave them in the car).
Do not use any abrasive solvents or cleaning solutions (liquid soap or window cleaner works best).
Wipe discs gently in only a radial direction (a straight line between the hub and the rim) NOT in a circle.