You know how I said Season 5 looked dated? Well, I want to correct some of the things I said. When I said it looked "dated", I meant in a technical aspect. When you actually compare it to the seasons before it, yes. It does look newer. The lines are more consistent, the colors are brighter, etc. But when you actually look at it on its own, it looks rather outdated, technically. Aside from being in a 4:3 aspect ratio, the lines are washed out and quite rough, and the colors are quite pale. Its also prone to animation errors.
Actually, Season 6 looks older than Season 5. Now pretty much everything is washed out and dull. The only episode that technically looks like it would be released today is Truth or Square - and even then, it has rougher lines.