Here’s a little-known fact: The water we swallow never actually touches our vocal cords! Everything we swallow actually lands at the base of our tongue and travels around the larynx (or voice box) and down through the esophagus where all the food all goes. However the motion of human swallowing is what helps raise and tip the larynx, thus dislodging mucus and leaving us feeling fresh and clear down there in the back of our throats.
You can see why turntablists like scratching “ahhhh” and “fressssshhhh” so much — they’re structureless slabs of tuned white noise, so they’re more forgiving. Scratching a rap a cappella is another story. The words have meanings, and the pitches have a musical context. When a word falls in the wrong spot or with the wrong emphasis, it sounds much worse than a wrong note in a jazz solo, and an untrained listener is more likely to notice it.