In a lawless era, some characters are struggling to impose order while others take advantage of everyone and every situation. Swearengen is the king of manipulators, and even the "good" guys struggle between right and wrong. Plenty of racism and sexism.
The body count (from accidents, disease, and disputes) is impressive. Murder (often bloody) and gunfire are common. Various depictions of rape and violent sex.
Nudity, vulgar talk, some brutal and blatant scenes (including group and fetishistic sex). Breasts, butts, and male genitalia sometimes visible. Sex is dirty and rough, and prostitution is part of the everyday landscape -- sex was a commodity in lawless Deadwood.
Never has "f--k" (and every other swear word under the sun) been heard so often or used in so many ways. Sailors would blush.
No products, but lots of gambling.
Drinking, Drugs & Smoking
Plenty of carousing, smoking, drugs, and drinking. Some characters are addicts.