Other mistake: Season 1, Episode 1: "Hot Tub". Just before Toot starts her earthquaking Charleston, look at Spanky Ham in the background; for a few seconds, his eyebrows are missing.
Other mistake: Season 1 Episode 1 "Hot Tub" When the characters stand all together in one frame at the end of the introduction, zoom in on Princess Clara; here she definitely misses her eyebrows.
Dirty Pranking Number 2 - S1-E6
Other mistake: Season 1 Episode 6: "Dirty Pranking Number 2". When the pizza delivery man shows up at the police station, the receptionist says that they hadn't ordered twenty pizzas; but the pizza man is holding only eighteen boxes.
Dirty Pranking Number 2 - S1-E6
Other mistake: Season 1, Episode 6: "Dirty Pranking Number 2". When the King intends to take Clara home, there are secret service agents jogging alongside the carriage. But in the first scene where it is seen, the agent on the frontal left of the carriage looks like he's hitching a ride, since he isn't hopping. In a later close-up of the King inside the carriage, an agent can be seen outside hopping up and down as he keeps jogging.
Answer: You might think it has something to do with licensing rights for the characters. But that's doubtful as several of the characters, both seen and unseen, are from the same animation company, Hanna-Barbera. Actually, it's a play on the real-life reality TV show convention of blurring/obstructing the faces of people who haven't legally consented to having their image shown, because their appearance on camera would put them in a compromising position. This happens often in shows like "The Real World, " "Cheaters, " and "COPS." In "Drawn Together, " Snagglepuss and Elmer Fudd, for example, were jokingly portrayed as not giving consent to their image on TV because it would out them as gay in the context of that episode. Of course, to the viewer, it's obvious who they are, and the humor lies in our memory of them as possessing a lot of stereotypically "gay" characteristics. Charlie Brown's face was obstructed by a leather BDSM mask, part of his "costume, " in a scene where Foxxy was his dominatrix. In the same scene, Natasha Fatale has Captain Hero in a similarly submissive role wearing a spiked collar and leash. Her eyes have a black bar across them, again, so as to "conceal" her identity, the way they do in the fashion magazines, even though we the audience know exactly who she is. The other characters you mention apparently "gave their consent" to their image being shown.
Michael Albert