I personally am not a fan of the following, although I won't ever stop reading a story if I ever see them. If I stop reading a story, chances are there is a lot more wrong with it than simply a word choice I'm not fond of. Anyway...
-Come - I much prefer using the term 'cum' (cumming, came, etc.) instead. If someone bellows "I'm coming!" or "I'm going to come!" I immediately think... is someone arriving? Where are they arriving from? I realize the widespread use of come vs. cum, but in general, it just bothers me because I feel as though the term 'cum' has evolved separately, and it should now be fully recognized as a word that can be used as a noun, verb, what have you.
-Overuse of either "pussy" or "cock" - Now, during a sex scene, I realize perfectly well that it isn't easy to keep one's vocabulary banks and wits in perfect reserve. For me at least, if sex looks or sounds good in my head, I'll get sidetracked during writing it because I just end up getting all randy. It sounds weird, but it happens. On that note, I can see how it's easy to say something like: John shoved his cock inside Mary's tight pussy without warning. His cock was so hard and he could feel the folds of her pussy enveloping him completely. He started working his throbbing cock in and out of her wet pussy until finally...
You see what I mean? There are many ways to refer to a penis, and even in nonconsecutive sentences, I much prefer to avoid overusing a single term. If I'm going to refer to body parts, whether they're breasts, penises, vaginas, whatever, I like to mix up the terminology so as the readers don't get distracted with overuse.
-Suckle - I fucking loathe this word. I associate this word with infants of any species nursing on the teats of their respective mothers. Also, it seems like such a bloody weak action.
"He suckled firmly on her neck."
or
"John suckled Mary's nipple into his mouth."
Tell me, what in the hell is wrong with just plain kissing? Or sucking? Or nibbling? Or smooching? Or "breathing-in?"
Suckling also reminds me of the business end of some sci-fi plant vine literally suckling the body fluids out of an unsuspecting prey, siphoning out its life energy or something.
Ugh, I just can't stand that word. I hate saying it, I hate reading it, and I think it can be replaced with much sexier, stronger, and more satisfying words.
Like I said, though. I'm pretty tolerant as far as my reading is concerned, but when it comes to writing, I just avoid certain things like the plague. I tend to overuse the "for all he/she/it was worth" euphemism, as it appears at least once in most of my stories. Other than that, it's all good in the hood. Or something.