Semen Taste Issues:
First off, do not eat asparagus if you want your semen to taste good within a day or so after consuming it.
"Consuming pineapple and/or parsley helps sweeten the taste of the male ejaculate. Can there be any truth to this and what other foods affect the taste, for better or for worse?"
Yes, what you eat can influence the taste and smell of your ejaculate. This is something like the smell of your sweat on the next day of a heavily spicy and garlic full dinner.
Because the average ejaculate consists mostly of protein, citric acid, fructose, sodium, chloride and smaller amounts of ammonia, ascorbic acid, acid phosphates, calcium, carbon dioxide, cholesterol, prostaglandins, creatine, and other minerals and chemicals which are produced by the prostate gland, cowpers gland, testicles and many other parts of your body, but shortly by "your body", and your body can only use its stocks and what you eat as its raw material.
Of course, every body has its own formula to create the semen, but eating less meat (and proteins) and more carbo hydrates, vegetables and fresh fruits may improve the taste and smell. For example parsley is a healthy plant and may also help to make your body juices more sweeter.
In general, dairy products create the foulest tasting fluids, alkaline based foods as meat and fish produce a butter, fish taste. Fruits and quality alcohol are good for a pleasant, sugary flavor. Chemically processed liquors may cause an acidic taste.
As said previously, ejaculate containing sperm has a unique individual taste for each male. Some males have bitter tasting ejaculate, tastes burnt, sour and strong. Other males, primarily vegetarians have ejaculate that generally tastes sweet, nut like. But to produce healthy semen your body will need some protein rich in zinc anyways.
A strong smell may also indicate an infection in genitals and you should urgently visit a gynecologist without losing time in the search of the magic formula!
Of course your body's duty is not to produce tasty semen, but healthy and productive sperms. Everything healthy and good for your body is healthy and good for your semen. Drink mild water on the morning and keep drinking more water than usual in the day, this will also help your bowels and your body to detoxinate. Eat less meat, more vegetables, drink less alcohol and stop smoking.