I don’t like bashing particular consoles but I had a particularly annoying experience with the PS2 slim. I purchased one, used admittedly, back in 2007 and for awhile it worked great, but I didn’t use it that much as I had mostly moved on to the 360 and the PS3. Eventually it stopped playing certain PS2 discs, including God of War 2, Gran Turismo 4 and a copy of Rogue Galaxy that I had also purchased used. I took that copy of Rogue Galaxy back 3 times and exchanged it before I hit upon the idea that the problem might not have been the discs, but the system itself. I also realized that all the games I was having problems with had something in common, they were all dual layered DVDs.
After doing some digging I came across a lot of people who said they were having the same problems. It turns out the DVD drive in the PS2 slim apparently has a much weaker laser, or at least one that’s prone to failing, as this was a known issue with the system. I gave that system away to some friends and bought one of the old PS2 systems and it’s worked great on everything I’ve thrown at it.