Quite often - more often than you might think - we get a submission with a "comedy" score. We find that in the more expensive submissions, where a filmmaker is able to afford live instruments (or a very expensive keyboard), the composer has chosen to use pizzacato, or the plucking of string instruments to indicate comedy. Sometimes woodwinds will substitute for the strings, providing some whimsical musical padding in the background.
We could go into a whole discussion about the role of music in film here, about how often music is overused to amplify an emotional or atmospheric effect which the director has been unable to achieve. In short comedy films, this music (almost always with "classical" instruments) is telling us: "Look how whimsical and quirky these characters are! What a funny situation! This is a comedy folks, can't you hear it?"
Every once in a while we receive a well-produced, well-written, well-made, and well-acted film which has such a "comedy" score, and we show it, in spite of the fact that the score bothers us. For the more expensive student films and many of our high budget submissions from LA, the music approximates what might appear in a Hollywood feature, since the film is being created as a calling card for the director, showing how "professional" and "slick" his or her production is. And a "comic" orchestral score is one of those elements the filmmaker chooses to spend money on.
But most of the time, such a musical choice points to larger problems with the film-- that the filmmaker is relying on the music to indicate the whimsy of an otherwise unwhimsical product. The hope is that by padding a scene with the comical plunking of strings (or the staccato of playful woodwinds) the viewer will be tricked into thinking that the scene is whimsical and the unremarkable characters are in fact quirky.
The best comedies don't shout "COMEDY!" while they're going about their business. They're simply telling a hilarious story. Pizzacato strings are never hilarious. A comedy score is a placeholder for hilarious.