Just use regular lube, that will work just fine.
Spitting is a universally recognized sign of contempt. When you see spitting in porn it's symbolizing that the other person is just a sexual object who isn't worthy of respect.
Okay, now that I got that out of my system, I had my first really sloppy, sputum loaded BJ this summer and it was kind of cool. It was part and parcel of a great performance and it was both erotic and a little dirty. But the boys didn't like the gook that nearly drowned them. The next time I'm asking for the "dry" version. She was from L.A. If that means anything.
Kinda gross not exciting at all