Vinegar and baking soda are both reasonable good cleaning agents because they are acidic and alkaline, respectively. A slurry of baking soda is also useful because it is abrasive and thus useful for scrubbing. I don't see any advantage in forming a vinegar-baking soda mixture though. You'll immediately form water, with the excess reagent determining the final pH. Sodium acetate might have some utility as an abrasive agent if there's any left in solution after the reaction is finished, but you could just use baking soda if it came to that.
Personally, I think people use vinegar-baking soda mixtures because they don't understand chemistry and figure if both are decent cleaning agents separately, then together they must be even better. Some of the same people probably figure mixing ammonia and bleach together will give a great cleaning agent, to much more deadly effects.