One thing that often makes it difficult to take erotica seriously is the vocabulary. Using the correct anatomical terminology for the genitalia is likely to come across as a bit clinical, but any euphemism or informal term is unlikely to appeal to all readers. I remember a friend at school regaling us with a story from a porno magazine he had acquired, where the male protagonist had removed his enormous tool from his trousers, and the reader had only realized after some time that this was his penis rather than a DIY implement.
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What one finds acceptable is likely to depend on personal preference and upbringing, and there are bound to be enormous regional variations in the English-speaking world as to what's used and what isn't. "Cock" or "pussy" might be fine, or a bit uncomfortable, or downright amusing.
But this is a multimedia age. Rather than all the wordy, often embarrassing descriptions of sex, why not use modern technology to save the effort of turning the author's mental image into the readers'? Sales of erotic novels are far greater for e-readers than for paper copies, so that it's possible to digest them in public without everyone around knowing what you're reading. So authors could commission their own photoshoot or movie snippets; or these days there's plenty of free porn out there on the web. "Yes, that's just the sex scene I was going to write, so drop it in and I can save writing 2,000 words! All I have to do is top and tail it." And not one mention of a... well, better not say so as not to cause embarrassment.
"Come here," she said, huskily. "I have a present for you."
That was amazing," he said. "Next time, shall we leave the lights on?"