Uncomfortable words are perfectly correct and not obscene. Nevertheless, they often surprise–or even shock–the reader. Sometimes they make the reader uncomfortable. These latter words can simply be highly personal. My high school English teacher was bothered by the word “bother.” She said it made her think of dirty old men. One of my personal preferences is to use “it isn’t” rather than “it’s not,” the latter sounding too much like “snot”–which is an uncomfortable word for a lot of people.
Consider succulent, flaccid, penal, ovoid, horehound, hump, abreast, coldcock, excretion, floppy, fondle, globule, goiter, lipid, niggardly, onus, rectify, and more.
Choose uncomfortable words for effect. Use them sparingly.