As a point of reference,
Gil is a reference to
Jack Lemmon's character in
Glengarry Glenross. He is the ultimate
frazzled,
over-the-hill salesman who can no longer cut it.
Gil (in my opinion) seems to be out there to replace all the bit characters that
Phil Hartman (RIP) played.
Hell, in a very recent episode (was it the one with the "
duff book of world records episode?),
Gil is now even a
lawyer (since there is no more
Lionel Hutz for
the Simpsons to use for
legal advice).
Just to add to the list of tribulations that Gil has been subjected to - when Homer and Marge have their sex-in-public-places fetish, they destroy poor Gil's hotplate when they make a hasty escape from the police in the used-car lots hot-air balloon.