All this is based on a very faded memory of something I read about five years ago on one of those “FAQ and Not-Very-F AQ About Sex” websites, and I am damn well not going to Google for it, especially considering the content.
Remember that the contents of ejaculate are a mixture of materials suitable for keeping a bunch of adventuresome sperm cells alive in out-of-body space temporarily while they make an Extra-Genital Activity. Parts are contributed by Cowper’s glands, prostate, and testes. If I understand this correctly, the Cowper’s gland fluid is relatively clear, of fairly low viscosity, functioning as lubrication (“pre-cum”) and then as the “base” for the mixture. The prostate secretion is a bit thicker, more viscous, and somewhat milky. And the testicular secretion contains the sperm and simply enough fluid to move them to the seminal vesicles where the seminal fluid is compiled from its sources.
The significance here is that the Cowper’s gland fluid was said to be almost tasteless, the prostate-derived fluid somewhat sweet, and the testicular fluid (“sperm” although it also had liquid present) was quite bitter. Hence the taste of ejaculate varies based on the relative proportions of the main ingredients. The testes produce on more or less a fixed production level (variable over long periods of time or with appropriate medication, of course, but not ramped up and down on a demand/supply basis). The other two glands produce essentially as called for.
When a man has a low sperm count, and he and his wife are attempting to start a child, he is often encouraged to abstain from ejaculation for a day or two before the “baby shot” (so to speak) to build up the proportion of sperm in the ejaculate.
Now, I am not betting the farm on the accuracy of my memory about this. But it would make sense that abstaining from sex for a day or two would serve to increase your sperm count, and therefore the bitterness of your semen, while daily or more-often sex would result in a lower proportion of testicular fluid in the ejaculate and a sweeter taste. Similarly, stimulation of the prostate would increase its secretions, with a similar effect.
I’d ask one of the M.D.'s, or a reproductive medicine expert if there is a Doper who is one, to vet the above, as I don’t want to emulate Handy in giving out false information, and the above is admittedly undocumented and based on memory of something read years before the time of posting. I’m offering it because I found it intriguing enough that it stuck in my memory, and if accurate would explain your question.