Cum does NOT taste sweet. Or hugely salty. Or creamy. It tastes primarily bitter with a trace of something gone bad. It's definitely an aquired taste. Having your virgin love it immediately without the guy having built it up into something of a fetish is rather unrealistic. There is a reason so many people won't swallow, and it ain't the texture.
Precum doesn't taste too bad... it has little actual flavor, just a bit salty.
Women have very little flavor as well, mostly a texture, which is extremely slippery which gives it a "greasy" mouthfeel.
You want a lubricant... look for something OILY.
Precum is actually quite slippery, but cum itself isn't. It dries quickly when spread out and has the consistancy of glue. Wanna use glue as a lubricant? I didn't think so.
Unless you are living in the Deep South in the middle of summer, or an aquarium, saliva dries very quickly. Spitting into your hand will not provide enough lubrication for comfortable buttsechs. Oral sex is only slippery because the spit is being continually applied. Pull away to give a hand job and after maybe a half dozen strokes or less it's already gone sticky, and it's easier to give a dry handjob than a sticky almost-dry one.
Water is sticky as well. It doesn't seem like it would be, but it is. Sex underwater is, well I wouldn't call it IMPOSSIBLE, but when my husband and I tried it, it didn't work. Too sticky.
Unless blood is flowing, it's not a great lubricant either... and it dries extremely fast... in fact it coagulates. It's designed to be sticky not slippery.
Soap DOES work as a lubricant, but it's mildly irritating. It would fall in the catagory of "better than nothing."
Apparently Herbal Essences Shampoo makes a good lubricant, and doesn't have the pitfalls of many other brands of shampoo. (LOL... thanks
kageotogi)
Wanna torture your participants... use alcohol. It STINGS. (Don't ask me how I know this).
Don't have oral sex or attempt a hand job after eating hot peppers. (Don't ask me how I know this, either).
Toothpaste is interesting to jack off with. Especially menthol toothpaste -- it leaves a cold, tingly feeling.