JonSpringon saidJack was meant to be a caricature of the stereotype. He needed to be every bit as flaming as he was to serve as a counterpoint to Will's non-flaming portrayal of a gay man.
Will had to be just as homosexual, but also a successful professional to Jack's out-of-work actor. Jack had to be oversexed to contrast with Will's lack of promiscuity.
I got offended, really, when they turned Will more and more into a vain, hair and image focused, OCD riddled, neurotic. They made him a different sterotype and THAT offended me.
Jack was just comic relief.
Some valid points. I'm sure the show's producers and writers envisioned Jack as a comic counterpoint to Will, and a balance against the equally eccentric Karen. And of course their goal was to win ratings at any cost, whereas creating a positive & realistic gay image was not very high on their agenda.
Jack's buffoonery did reflect badly on the gay community. Millions of US viewers who knew little about gays took Jack at face value. We gays knew how over the top, unrealistic and clownish he was, but did Middle America?
So that while I did find Jack's antics funny at times, to answer the OP question - yes, I did think that overall the Jack character was offensive, and detrimental to gay image & interests.