A quotation from How A Woman Loves To Be Loved, by Angel Smith (Warner Books, copyright1973), page 73:
"A load of sperm is sticky, bleachy and stringy. It has the consistency of raw egg, and just the way you don't always feel like a mouthful of raw egg, so some women don't always feel like a mouthful of sperm.
"Some girls never get around to liking it, and that's a fact you have to accept....
"[The author of] The Sensual Woman coaxes girls to shut their eyes, hold their noses, and swallow the whole load like good little sexpots. But, the whole point about swallowing a man's semen is that you do it because you really want to do it..."

and on page 74: "Male sexual hygiene, in my view, can be summed up in three little words: wash your cock.
"Apply that formula twice a day..."

Xaviera Hollander, in Xaviera On The Best Part Of A Man (New American Library, copyright 1975), titled chapter 14 "Keep It Clean As A Whistle Or It Won't Get Blown, and in it she wrote: "There's something else about a man's genital odor that few are aware of. It's the scent of their semen. The way it tastes or smells can depend a lot on what they eat or drink. If a man eats spicy foods or drinks a lot of alcohol, it tastes unpleasant and sometimes even bitter. But, if he drinks a lot of fruit juices and eats sweet things like caramels, creamy pastries and chocolates, the semen won't taste like chocolate, of course, but it will taste nicer and more delicate....Darling, eat lots of delicious peaches and nectarines and drink fruit juices so it will go right down to your groin."

There's a third reference that I can't seem to dig up, in which the female author also recommended that guys who want blowjobs should eat chocolate daily, and it finished with, "Wash your cock. Twice a day."