When you decide you want to write about sex, or at least include sexual content in your work, you must find a level of explicitness at which you're comfortable. Not to mention if you pursue a traditional publishing deal, many publishers have their own levels and of course, there is no standardization or consistency and their definitions are not always perfectly clear. I get it, it's a subjective thing, and what I find tame, someone else may find shocking or offensive.
So, if I were in charge, I'd set up the gradations of explicitness by restating the same sentence as an example. Tongue in cheek, people, tongue in cheek.
FRIGID (Medically correct)
He inserted his erect penis between the labial folds of her vulva into her vagina.
Nobody wants to read that, do they?
COLD (Purple prose)
He introduced his stalwart staff to the delicate flower of her womanhood.
Are we having sex or gardening?
LUKEWARM (deliberately vague)
He entered her.
Into a contest?
WARM (a little more descriptive)
He pushed himself into the warmth of her core.
Now we're getting somewhere!
HOT (No doubt about what's going on)
He thrust his hard cock into her waiting wet pussy.
*fanning self and blushing but reading on*
SCALDING (not for everyone)
He pounded his enormous prick into her tight, juicy cunt.
Wait, WTF am I reading? I thought this was a love story.
The parameters of the upper levels seem to hinge on whether or not you use the "p" and "c" words for female anatomy. I'm assuming that's because most erotica readers are female and some are offended by these words. Personally, I'm okay with them unless they are preceded by a derogatory adjective. Nobody wants to hear "stupid cunt" but "beautiful pussy" ain't so bad, huh?
In my writing, I've found my sentimental style conflicts with really hard -coe terminology so I tend to stay away from Scalding. It just depends on the story. You don't wear combat boots to a tea party.