It is the home of the Ku Klux Klan, 19th Century secessionist traitors, rattlesnakes, alligators, conservatives, and many ignorant voters. Black people and LGBT people there may face discrimination. (Unlike New York City with its stop and frisk policy?) The Deep South means something similar to The South but there are differences. 
Culture good and bad
The South is known for having no cultural achievements whatsoever. No, we didn't really mean that; the South has some cool music, some great literature and some of the best cooking in the country. It is the Birthplace of jazz and zydeco, Ralph Ellison and Harper Lee, and Cajun and Lowcountry cuisines, it punches above its weight in doing battle with the Wonder Bread tendency of American culture. Just to be sure you get that last point. Wonder Bread was invented in Indianapolis, Indiana. Just try hating on the South while you sit at the Cafe Du Monde having cafe au lait and beignets. Sneer at our lack of culture you Yankees whose contributions to world culture include the city-wide food desert of Camden, New Jersey.
Not all good
Southern hospitality is supposed to be good. What does that mean? It means looking after people who are well off and don't need help. Poor people in the south may have to get by on soup kitchens. Southern cuisine is supposed to be good and their needlework is good.  What does that mean? It's part of a bad tradition that women are supposed to spend practically all their time cooking, sewing, looking after kids and doing women's work and being subservient to their fathers before they are married, being subservient to their husbands afterward, see Phyllis Schlafly. If you're a woman and like needlework and stuff we think you should do other things as well.
Question: Basically, liberals would be okay with the South if they just stopped having Senators. Deal? Answer: Writing off the majority of Southerners is a bad habit of Yankee elites that began Southerners were first abandoned at the end of Reconstruction. Let's skip blaming the victim.
Stereotyping is frequently the result of ignorance, and people from outside the USA don't always know enough to tell when a stereotype is incomplete. The bad stereotype underestimates what's good in the South.
The South supported Slavery and fought to continue it during the American Civil War. These states are also called the Slave states, their enemies were The North. It used to be considered a "safe haven" for the Democratic Party in many presidential elections before the 1980s when racism plagued the political party.