Twice in my 9+ yrs on the left side I have refused an a/c for this kind of thing, both times when I was with an FAR 121 operator.
The first time I was with a bottom feeder Pax/charter outfit out of S. Florida. I came to the a/c and the F/E reported it was "trashed" and there were roaches crawling all around her desk. The plane had been parked in Mem overnight, and the previous crew were obvivously pigs, as there was evidence of crew meals all over the seats and floor, as well as peanut shells and crisp wrappers, etc, down around the base of the control yoke and rudder pedals. And yes, there were roaches. My logbook entry went something like "trash and food left down around flight controls, roaches crawling around cockpit and in F/E's desk, cockpit deemed unsanitary for continued safe operation."
The second time was when I was under contract to an FAR 121 cargo operator. After continued complaints re: cigarette butts and ashes left scattered around the cockpit. This happened each time the a/c came out of maint. One day I told the base manager enough was enough, and although I didn't make a write-up or delay the flight, I did observe the base manager personally cleaning the cockpit.
So I guess I am fully in support of the actions of the skipper in question. No one has said how many times this has occurred previously, or if this skipper had verbally reported the same situation before with nothing being done.