I always heard it was Arius that St. Nicholas slapped, at the 1st Council.
Regardless, you are absolutely right that these guys were deadly serious -- they were not sitting around smoking cigars and agreeing with each other out of politeness.
Ah, that's right. My bad. For some wierd reason, I get certain details of those concils (1st and 3rd) confused. Perhaps it due to the dream [some of] the bishops had at the 1st, where the BVM asks them to forgive St. Nicholas and let him back into the council.