Not 'bad gas' per se, but yes, it was the gasoline.
Your rochester carb probibly lost its nice protective coating years ago (its now a dull grayish color, right?) that's the pot metal (not really zinc, more like 'zinc-y stuff') at that is susceptible to damage by ethanol.
ALL GAS is ethanol free right up to the point they pour it in the tanker for local delivery. Its at that final transfer station they dump the garbage that is ethanol into it to get whatever E rating they are required to sell.
This is, in addition to what others have said.. the ethanol WILL 'clean' your tank an all that gunk will make it to your fuel bowl and settle out... but most of it is the direct attack on the metal by the ethanol.
Adding an inline filter is still needed, but it won't stop pot metal, die cast carbs from getting damaged.
