I have an old PS3 from when they first came out, I dust it regularly and had 0 problems playing for 5 hours straight. Imo since most problems seem related to older PS3s, sounds like some people aren't keeping them clean.
I recently opened my ps3 up to clean it out. The fan would start getting real loud when watching netflix or just idling. There was enough dust in there to build myself another cat. After cleaning it out it doesn't sound like a jet engine anymore. It seems like whenever sony outs an updated firmware people claim foul.