I used to watch Spongebob when it first came around. It was OK then. Actually, I found out that Patrick was never mentally retarded in the early episodes. Yes, he was a dimwit, but now...now he's just......ugh.

The show had such horrible character development.
And I was sad when they tossed the ongoing jokes like the guys that screams "My leg!" when multiple people became injured.
Spongebob
was good, but has become colorful crap.
As for Cartoon Network, I think that the cartoons they aired during the 90's and some early past decade were good. Samurai Jack was brilliant. I have no idea why they didn't finish that series.
I loved Zim because it was so twisted. It was one of those shows that I liked, but I wasn't quite sure why.
Ed, Edd, and Eddy is a show that none of my friends or family seemed to like. I was usually only able to watch it when no one else was around.
Most of the shows that people have listed I enjoyed as a child and still do.
I even like most of the crappy cartoons that they had like Johnny Bravo. That show is obnoxious. Or maybe it was just Johnny that was like that... But I liked the stupidity when I was younger.
There's very few shows from that time period that I dislike. And I think that kids these days will say we're crazy when their older. They'll believe that the cartoons from when they grew up will be awesome. I have not yet heard someone say "Chowder is the best!" But that day will eventually come......
I notice that no one ever seems to remember Time Squad.