On paper Walter Peck is something of a tragic figure, but Willaim Atherton (especially in the 80s) was always typecast as a dick. It's no different with Peck, and instead of being tragic he comes across more as a petty, controlling man that assumes fraud and pays for trying to control something he doesn't understand. I think the smartest thing to do in-story would have been to take him along on a call to catch a ghost; which could have been hilarious, but that's neither here nor there.
Man, I loved Ghostbusters so much as a kid.
No real qualms with the movies overall; now I just need to figure out which one I'm going to watch since mentioning them makes want to fire up the dvd player.