Carter was widely considered a terrible President.
In the words of your personal hero, "There you go again", speaking for the mass public when you don't exactly have your finger on its pulse.
Widely among your set, no doubt; In the real world, he is considered not the worst and certainly not the best president. Arguably he is the unluckiest president since FDR (who made his own luck), since he had to deal with stagflation, an energy crisis, the Iranian hostages, and the ill-fated rescue attempt in the desert (which took down 4 marines and his re-election chances in one dust storm).
Also, if Reagan and the other traitors around him hadn't interfered with Khomeini, the crisis would have been over much sooner. But as is well known, the Reagan people got the Ayatollah to agree to keep the hostages until after the election. He did this by promising to illegally sell them arms, which of course the Reagan criminals did until they were exposed in the Iran/Contra affair.
Ever since Nixon, the Republican party has been a swamp of moral disease, but it came to a full fever under Reagan and his criminal gang.
Carter's approval ratings averaged over his time in office was, along with Truman, the worst of all Presidents since Truman's time. Truman was 0.1% lower. A different outcome of the raid would have improved his approval to a degree, but the stats were as of Jan 1977, so much of his approval polling was based on earlier months. To know more definitively, we would need to see the data from each month and project a boost in the months following the raid in April 1980 to come up with a new projected average.http://www.gallup.com/poll/116677/presidential-approval-ratings-gallup-historical-statistics-trends.aspx
He also fared poorly in debates with Reagan. In addition to the "there you go again", Carter also looked foolish mentioning that he discussed nuclear proliferation with Amy, age 13, to get her thoughts on it. As would be said using today's speak, "people were like WTF?"
Hard to deny that much of Carter's favorability today comes from post-president activities.