This one is typical:
Letterman had the ability to be very funny throughout his NBC years. During his first few years on CBS he was genuinely innovative and creative. ComedicalIy, I thought he had it all over Leno. Now, he’s just a mean, old man who likes to use his show to lash out at anyone (usually conservatives). You wouldn’t mind if he spread his venom among the whole political spectrum, but he’s just another shill for the liberals.
Letterman was funny early on much like George Carlin, but both slipped into, what? A combination of mediocrity and bitterness. I saw Carlin in person later on and he was almost unintelligible. He was reading off of cue cards he held in his hand and seemed unconnected to not only his audience but to where he was. They are two peas in a pod to me.
Decades ago Letterman had a daytime show on NBC. It ran throughout the summer of 1980 and was the funniest show on TV. It started as a 90 minute show but was reduced to 60 minutes and ended in the fall. I used to watch it with my mother.
The early Late Night was also very funny. He had a golden TV spot with no competition and could have stayed at NBC with as much $ as he ever would have wanted, but his ego and desire to concur at 11:30 forced him to be stupid and narcissistic. He never consistently beat Leno and it fed into his already disturbed sense of inferiority.