Stephen Pastis, the creator of Pearls Before Swine is a member of Team Cul De Sac. Richard Thompson, suffering from Parkinson's disease, had to take some time off from drawing his comic strip Cul de Sac to receive treatment, and a variety of his colleagues have stepped forward to help keep the strip going during his recovery.
In the 4/1 Sunday sequence, Pastis makes fun of his inability to mimic Thompson's loose style. (click on images to enlarge)
But I think the self-deprecation is more exaggerated than most people think. Check out a recent sequence from Pearls Before Swine. In the great East Coast/West Coast Cartoonist War, Pastis draws several characters from other strips -- and nails each style.
Beetle Baily, Cathy, and Dolly from Family Circus are all drawn with the characters in proper proportion. And note Mooch, the cat from Mutts. Patrick McDonnell's style is radically different than Pastis', yet the character looks right.
These panels show that Pastis can mimic other cartoonists' styles convincingly -- except when it serves the humor for him not to.