Carter got bashed because:
1) First and foremost, he told the truth.
2) He wasn't
bought, therefore, he was the subject of intense media propaganda funded by the wealthy to ruin his reputation and make sure he wasn't re-elected. It worked. What they wanted was a tool and a fool, which they got in Reagan.
3) He knew about energy, resources and the economy. He saw peak oil and all its implications and tried to do something about with speed limits, conservation programs and unflashy things that would actually help. People just resented being inconvenienced by something invisible that they couldn't understand and blamed him. Reagan's administration, in contrast, just increased government spending on the military and signed legislation to loosen lending practices of credit unions so that ordinary people would feel richer, by acquiring more debt (sound familiar).
http://www.presidency.ucsb.edu/ws/index.php?pid=418724) Carter told people they would have to sacrifice and that their lifestyles might suffer. They
despised him for that, just as people despise people who warn of peak oil now. Reagan's administration, in contrast, said it was "morning in America" and gave the country debt "money" in lieu of caffeine.
5) Carter is smart - a nuclear engineer, who didn't pretend to be dumb. People felt inferior to him, and resented him because of it. Reagan know how to act like the commonest of people. No intellectual intimidation there. Lower middle class and poor Americans hate people smarter than they are.
6) Carter did not kick Iran's ass. Lower class white America would have dropped a nuke on millions of innocents because a few of their leaders annoyed us and risked an all out nuclear war with Russia. Carter didn't. That made him look weak to a public weaned on WWII stories, still smarting from a defeat from Vietnam.