A nasty word to describe someone is vile or even malevolent or reprehensible.
Other nasty words that can be used to describe someone, especially for someone who is mean and unkind are vindictive, cruel and mean spirited.
For people that are deceitful or untrustworthy you can use two faced or conniving.
For rude or crude people you can use words like obnoxious or vulgar.
Reprehensible, contemptible and depraved are more formal words to describe a terrible person.
Some insulting adjectives are Asinine, Fatuous, Feckless, Puerile, Vacuous, Abrasive, Callous, Churlish, Condescending, Petulant, Derisive, glib, impertinent and Supercilious.
Supercilious refers to behaving or looking as though one thinks that one is superior to other people.
Impertinent is not showing proper respect, rude and bold.
Glib is being fluent but insincere and shallow.
Derisive is expressing contempt or ridicule.
Petulant is being childishly sulky, bad tempered and impatient.
Condescending is having an attitude of patronizing superiority.
Churlish is being rude, surly, and mean spirited.
Callous is showing a cruel and insensitive disregard for other people.
Abrasive is showing little concern for others feelings, being harsh or rough.
vacuous is having or showing a lack of thought or intelligence and mindless.
Puerile is childish, trivial and immature.
Feckless is lacking initiative or character, being irresponsible.
Fatuous is being silly, pointless and devoid of any intelligence.
Asinine is being utterly ridiculous or extremely foolish.
A fancy way of saying "rude" is insolent or even impertinent, especially for bold, defiant disrespect.
You can also use the word impolite for general bad manners and disrespectful for treating someone without regard.
For general bad manners impolite refers to lacking common courtesy or etiquette.
Discourteous refers to failing to be polite and considerate to others.
Unmannerly is a word that refers to showing a lack of good upbringing or social graces.
For insult and disrespect you can use words like disrespectful, which is showing a lack of regard or esteem for someone.
Insolent, can be used for referring to someone that shows a bold, insulting and arrogant lack of respect.
And impertinent is a word for being intrusive, overly bold or even presumptuous.
For being short and blunt you can use words like curt, brusque or tactless.
Curt is a word that you can use for rudely brief or abrupt in speech or manner.
Brusque can be used for abrupt and slightly harsh in speech.
And Tactless can be used for someone who says things, which are insensitive or likely to upset other people.
When it comes to Rough or aggressive you can use words like offensive, churlish and boorish.
Offensive is when someone is highly annoying, insulting or causes hurt feelings.
Churlish refers to rude in a mean spirited, surly or grumpy way.
And Boorish refers to rough, unrefined and bad mannered.