I'm pretty far to the left politically, but having lived for a while in the Midwest, my experience is that conservatives aren't on average any less nice than liberals. Having said that, it does appear that political differences have some basis in differences of personality and psychology. The dominant model of personality in psych research is the "Big Five" (sometimes summarized using acronyms like OCEAN or CANOE):

Openness: The tendency to be interested in new or novel ideas, to have a wide range of interests, to appreciate art, literature, culture, etc.
Conscientiousness: Self-discipline, persistence in pursuing one's goals, etc.
Extraversion: Level of social engagement; do you gain energy from social situations and interacting with other people, or do you tend to find it exhausting?
Agreeableness: The tendency to value getting along with others, to be generous, trusting, etc.
Neuroticism: The tendency to experience negative emotions like fear, anxiety, insecurity, etc.

Speaking in admittedly crude generalities, people who rate highly in openness tend to be politically liberal (which at least partly explains why liberals tend to dominate the academy and the arts, the "Hollywood liberal bias," etc.). On the other hand, conservatives generally rate more highly in conscientiousness (as such, they usually dominate business and the military). Liberals also tend to rate higher on measures of neuroticism, so it's not all good news for liberals. In addition, the Big Five are estimated to be 40%-60% heritable, so surprising as it may seem, differences in political orientation may in some small part be a result of genetics.

Well, there are very real and documented correlations that the higher level of education one receives is very often a predictor of more liberal ideology.

You then just trace education levels to certain geographies and it becomes self-fulfilling. Places like the South or the more rural Midwest that have lower education rates on average lean more conservatively in their political makeup (again, on average).