Things that do not work on PS3 include:

Spyro 2:
Audio in cutscenes turn off

Spyro 3:
One of the cutscenes will not load.
Sometimes a character will not finish their chat. So the game will skip and turn off the audio at the last second.

I got the game at the open market in Huddersfield along with Enter The Dragonfly. I put the disc in my console, and it worked fine. So I thought it was pretty decent even though it was from a market for a fiver. Once I unlocked Toasty, the first Artisans world music decided to start jumping. Later on in the game, I got onto Doctor Shemp. The music skipped and skipped and skipped. When I rescued that dragon before you start battling Doctor Shemp, I could not hear a word he said.
A. Because the music was skipping over his voice
B. The dragons voice was muffled and very quiet
But after I spoke to the dragon, the music stopped skipping. I got onto the second thingy where you flame Doctor Shemp, and then it started jumping and skipping really bad. It was skipping so bad, the surround sound in my room made it go all loud and it vibrated through my bedroom floor. Now, before you start saying "Your disk needs cleaning" I have cleaned it about 10 times, and it still skips. I usually get tips off my mum when it comes to this, but she can't figure it out either. So if you have any other tips for me, please let me know! Because the skipping and jumping is driving me up the wall!

Ok:

Get some vegetable oil, put it on the disk, and get a clean towel and whipe it. Whipe it all over the marks, then le it dry for around 3 minutes. Come back, and whipe it with a clean towel - and hey, your sorted.

(Also apparently it's common for Ratchet and Clank 2 to be slo-mo)

According to HERE, Spyro has Audio problems on a PS3. They recommend to update.