Install a good catch can to minimise this.
The fuel never touches the intake manifold, intake ports or the top of the intake valves.Because not 100% of the gasoline is burned during the combustion process.
Poor quality fuel may leave unburned elements to stick on the valves and ports and BG 44k may help reduce this.
There is no proof that top tier fuel or additives reduce carbon buildup but if Audi recommends it, I figure I'd give it a try. There are also proven benefits to using top tier fuel and BG 44k for fuel the system and injectors.