This tip actually comes courtesy of Netflix, after they were beginning to kill me by sending unplayable disc after unplayable disc. The first offender, (a How I Met Your Mother DVD, if you must know), refused to play in my DVD player, so I pulled out all my tricks to clean it (except for the ol' toothpaste trick, which I was tempted to try, but since I didn't own the disc, I had reservations), to no avail, so I reported it unplayable, and Netflix sent another copy of the DVD.
Would you believe it, the next HIMYM disc they sent would also not play! By then I was angry and cursing the Netflix gods as I signed in to my profile to tell them yes, you sent me another crappy DVD that I can't play. But instead of them telling me OK, they'd send a new one out (as they had the previous time) it was as if the website sighed loudly at me; the next message I got was something along the lines of "Have you tried Windexing it?" Defeated, I admitted I hadn't, so I tried it.
To see the rest of the tip, just read more.
I pulled out the Windex (I hear ya, I am trying to get rid of it and replace it with the green version but that bottle drains so slowly), spritzed it on a paper towel, and wiped away, being careful to not leave too many particles from the towel on the disc (next time I'll use a soft cloth and avoid more potential scratches with the paper towels). I placed the DVD into the player, and like magic, the disc played.
I'm curious, have you heard of this tip before? I was surprised I hadn't! For the concerns about using window cleaners on a disc, a quick Google doesn't yield much evidence saying it will damage anything, but if you're concerned, do go with an eco-friendly (and therefore, less chemical-y) window cleaner, as I'd imagine it would have the same effect as the commercial cleaner that I used.