CD de-scratching machines - any good?

I don't know about cd de-scratchers but I did get a (probably more primitive) gadget for $16 that claims to "clean" a cd of all it "defects"; and I have to admit, for small scratches, it works amazingly well. My cousin left a cd-r, siny-side up, on the floor of his sad sad hooptie chevy and ended up getting gravel, dirt, grease (from both car and french-fry) and sneakerprints all over it. I cleaned it off with my cleaner gadget and it plays just fine.
Granted its a bootleg of a bad concert by a really bad local rap group, but the cd doesn't skip and plays well.

Oh, side note: If your OS of choice is Linux, you can use an app called cdparanoia instead of X11Amp. It does an amazing amount of error correction and I bet I could've played my cousins damaged cd-r even before cleaning it if I played in cdparanoia.

There's a similar (free) package for Windows called Exact Audio Copy. This also depends on the player/drive - my Plextor CD-writer does a worse job than my Asus CDROM but better than my old Sony CD-writer.

But anyway, sometimes software doesn't help. The underside of a CD is made of quite simple and common plastic, polycarbonate, which isn't particulary 'vulnerable'. Any polishing fluid that is suitable for plastic surfaces will essentially work. I've always used car polishing fluid, which usually does the job although deep scratches along the groove are almost impossible to fix.

Basically, use a little fluid at a time and use a soft cloth to wipe in soft but firm small circles. Don't rub in large circles 'along the groove' because irregularities in that direction are far more difficult to read/correct for the player than angular scratches. And clean the CD before you play it - you don't want polishing fluid flying around inside.

These commercially available packages are based upon the same thing, but do the hard work for you. They do work as advertized, but don't expect miracles. Generally there's a lot of hoopla about their 'patented polishing fluids' (= lots of $$$ for refill bottles) but you can take that part with a grain of salt - we're not talking about exotic materials here.

I've heard reports of using toothpaste (which is indeed basically a polishing substance with various healthy additions), but I'd only use that as a last resort (if only because it doesn't say on the tube if it's suitable for plastic surfaces).

"ARE YOUR COMPACT DISKS GETTING THEIR MINIMUM DAILY REQUIREMENT OF FLOURIDE?"
"If not? Try New Colgrate CD Cleaner with extra Tartar Sauce Protection!"
"Just slather it onto the CD, scrub vigorously with a clean peice of very fine sandpaper, rinse, repeat. Voila! Now your lo-fi indie band sounds like the Boston Pops! But wait theirs Less...."

There's a similar (free) package for Windows called Exact Audio Copy.
Actually, I think EAC does something different, but I'll have to look it up.
This also depends on the player/drive - my Plextor CD-writer does a worse job than my Asus CDROM but better than my old Sony CD-writer.
Ah...note to John Barlow...after you clean your CDs, don't forget to clean your CD player. Not only are their "lens cleaner cds" ($11 - $25 bucks) but also a can of compressed air (roughly $3 - $5) to blast the dust bunnies out.

I used to work at a record store that had a professional scratch removing machine that actually would remove every scratch, fixing every flaw except the gouges that went so deep that if the disc was held up to the light one could see right through it. Obviously nothing could fix those. So, yes, machines like that can work, but I'm not sure if anything one could buy for oneself would work nearly as well (the one at the store must have cost about $1000).

Dan, there is a way that is sometimes able to fix those see through holes. It all depends on their size, but what you have to do is to get just enough tin foil to cover the hole and place the shiny side of the foil facing the label side, of the CD. Then get the thinest sellotape you can find and place over the foil making sure it is as snug as possible. With a bit of luck the CD player is able to get enough information from either side of the gap to error correct the missing information. Give it a go, it's worked for me before. A word of warning, don't put too much foil or tape on as you can imbalace the CD, which will confuse the player more than the hole.

Too many 'holes' in that last post.

Yeah, the reason that works is that there's enough error correction in CDs that you can lose about a 1 mm hole's worth of data in 1 spot & still re-create the missing info. Whatever is reading the CD uses the redundency /error correction bits on either sides of the hole to fill in in the missing bits.