BabySmitty
Porous Freak
I thought I'd do a post illustrating what went wrong with Spongebob's character design. This largely has to do with who's drawing him and what his model sheet looks like. So take it with a grain of salt.
oh look at this, he's got a nice goofy design, very cute and awkward-looking
his pilot design takes what was charming about his rougher design, and polishes it slightly, while keeping some of the wobblyness

His early show design from season 1 polishes his pilot design a bit, but still retains the wiggliness

His design in early season 2 looks very similar to his season 1 design. Despite the show's transition to digital ink and paint, his design still looks organic. His color is a bit washed-out, but we can chalk that up to malnutrition and Krabby Patty-induced anemia.

Spongebob's design in season 2 also brought us the distinctive Greenblatt Spongebob. His design originated in an episode directed by Erik Wiese, so... perhaps his chubby-cheeked design was the decision of Erik, or maybe even Hillenburg himself. This design has the tendency to frequently go off-model in humorous, cute, and appealing ways, and is fun to watch.

Starting in mid season 2, Spongebob lost a lot of his organic imperfection, leading to a very polished yet very stiff design.

In season 2, it was like someone took an iron and ironed out Spongebob.
http://www.sbmania.net/pictures.php?img=Tf30waiBZcuAIT1vWPTWVj7UVKyODRwIF+YlIAgmF5c=
Season 3, (with mostly Greenblatt's episodes as an exception,) gave us a Spongebob design that was stiff as a board and very rigid-looking.
http://www.sbmania.net/pictures.php?img=wZZ1lNg2BrBh9VSvtagYUFtVkqwmrVLd2WMlA4aoB7g=
Spongebob's design in the first movie is ... odd. Proportionately he looks much shorter, his cheeks are chubbier, he looks more box-like; but his face is extremely expressive. He's got Sherm Cohen's fingerprints all over him. His body shape is also a LOT less consistent. It changes from shot-to-shot.
http://www.sbmania.net/pictures.php?img=XxMtsz+0e/TJ5u7gTdCI0PXOhfkfWk2CFlG6quaFe90=
In season 4, Spongebob's design looks like a mish-mash of his movie design and Greenblatt's design. He isn't too stiff, and he's very expressive. His proportions seem to change frequently, too.
http://www.sbmania.net/pictures.php?img=ATchgTupZMFDutyYvsUJFQj/aPHH9hfVpKnll0udmHA=
In season 5, Spongebob's design is pretty similar to how it was in season 4.
http://www.sbmania.net/pictures.php?img=NM7caC60rFy8yYfTwLAOQlg81FOfSApqiu+9TbCbtyA=
In season 6, something went really, REALLY wrong, and Spongebob turned into.... this...
http://www.sbmania.net/pictures.php?img=/0DOf6M4ur/fwpCuAvWJQRum4wEC0cVY4icB8hUnlQg=
His eyes got smaller, his eyelashes got thicker, his proportions and shape became much more rigid, and his eyes look.... dead. This design carried into season 8. Why, Aaron Springer?!
http://www.sbmania.net/pictures.php?img=9V/kY04nG/aDJfUhp0RWYvIUgx2cBq8gYuZ1AycEFp0=
Poor, ugly thing. Even in the highly-regarded episode "Treats!," Spongebob looks UGLY.
http://www.sbmania.net/pictures.php?img=Aa4zjht1/Sp4BH6nReXBzP+ejEjgZV0e2AOc1Z0E66Q=
As much as I hate "Sponge out of Water," it gave Spongebob's design a much-needed makeover. Sherm Cohen came back on board to make Spongebob look cute and huggable again.
And fortunately, his shiny new design has carried over into the post-second-movie episodes.
https://www.youtube.com/watch?v=VKcqoNL8enA
oh look at this, he's got a nice goofy design, very cute and awkward-looking

his pilot design takes what was charming about his rougher design, and polishes it slightly, while keeping some of the wobblyness
His early show design from season 1 polishes his pilot design a bit, but still retains the wiggliness
His design in early season 2 looks very similar to his season 1 design. Despite the show's transition to digital ink and paint, his design still looks organic. His color is a bit washed-out, but we can chalk that up to malnutrition and Krabby Patty-induced anemia.
Spongebob's design in season 2 also brought us the distinctive Greenblatt Spongebob. His design originated in an episode directed by Erik Wiese, so... perhaps his chubby-cheeked design was the decision of Erik, or maybe even Hillenburg himself. This design has the tendency to frequently go off-model in humorous, cute, and appealing ways, and is fun to watch.
Starting in mid season 2, Spongebob lost a lot of his organic imperfection, leading to a very polished yet very stiff design.
In season 2, it was like someone took an iron and ironed out Spongebob.
http://www.sbmania.net/pictures.php?img=Tf30waiBZcuAIT1vWPTWVj7UVKyODRwIF+YlIAgmF5c=
Season 3, (with mostly Greenblatt's episodes as an exception,) gave us a Spongebob design that was stiff as a board and very rigid-looking.
http://www.sbmania.net/pictures.php?img=wZZ1lNg2BrBh9VSvtagYUFtVkqwmrVLd2WMlA4aoB7g=
Spongebob's design in the first movie is ... odd. Proportionately he looks much shorter, his cheeks are chubbier, he looks more box-like; but his face is extremely expressive. He's got Sherm Cohen's fingerprints all over him. His body shape is also a LOT less consistent. It changes from shot-to-shot.
http://www.sbmania.net/pictures.php?img=XxMtsz+0e/TJ5u7gTdCI0PXOhfkfWk2CFlG6quaFe90=
In season 4, Spongebob's design looks like a mish-mash of his movie design and Greenblatt's design. He isn't too stiff, and he's very expressive. His proportions seem to change frequently, too.
http://www.sbmania.net/pictures.php?img=ATchgTupZMFDutyYvsUJFQj/aPHH9hfVpKnll0udmHA=
In season 5, Spongebob's design is pretty similar to how it was in season 4.
http://www.sbmania.net/pictures.php?img=NM7caC60rFy8yYfTwLAOQlg81FOfSApqiu+9TbCbtyA=
In season 6, something went really, REALLY wrong, and Spongebob turned into.... this...
http://www.sbmania.net/pictures.php?img=/0DOf6M4ur/fwpCuAvWJQRum4wEC0cVY4icB8hUnlQg=
His eyes got smaller, his eyelashes got thicker, his proportions and shape became much more rigid, and his eyes look.... dead. This design carried into season 8. Why, Aaron Springer?!
http://www.sbmania.net/pictures.php?img=9V/kY04nG/aDJfUhp0RWYvIUgx2cBq8gYuZ1AycEFp0=
Poor, ugly thing. Even in the highly-regarded episode "Treats!," Spongebob looks UGLY.
http://www.sbmania.net/pictures.php?img=Aa4zjht1/Sp4BH6nReXBzP+ejEjgZV0e2AOc1Z0E66Q=
As much as I hate "Sponge out of Water," it gave Spongebob's design a much-needed makeover. Sherm Cohen came back on board to make Spongebob look cute and huggable again.
And fortunately, his shiny new design has carried over into the post-second-movie episodes.
https://www.youtube.com/watch?v=VKcqoNL8enA