I recall learning about the origin of carpetbagger when studying history in school. I find it kind of odd looking back that we were taught a very Neo-Confederate view of Reconstruction given that I was in a Northern state.
Yeah, it was the same for me -- as a kid in the '80s and '90s, I saw and read a lot of that kind of thing and you don't automatically question all of it, not when that's often the only view of things you're getting. That school of thought is still out there, but it has faded.
You see, from the post Civil War era through most of the 20th century, history of the Civil War was dominated by historians from the South. So, even up here in the North we learned bad things about the carpetbaggers (I remember this as well), were told about how Lee was almost a tragic hero who didn't really like slavery, Grant is pictured as a drunken bum, etc, etc. This version of history lasted a long time, and many Northerners believed it. There are innumerable academic examples, but just look at two of the most prominent Northern things about the Civil War from the '70s and '80s, The Killer Angels (the book, or the movie Gettysburg based on it) and Ken Burns' Civil War documentary series. I loved both of them at the time, but looking back they repeat far too much of the traditional Southern version of the story without questioning it much. The Killer Angels has a line in it about how Lee doesn't really think much of slavery or something along those lines for example, and is sympathetic to both sides. Kem Burns' Civil War is, too often, similar.
In the past couple of decades though, that version of the war
finally has started to fall apart. Lee's image, outside of the South at least, has gone steeply down. For example, there has been a good amount of reporting on Lee's true view of slavery -- he was strongly in favor, and did not treat his slaves well. Grant's good qualities also have drawn attention, such as the fact that he won the war, that he wasn't a drunk, and that he worked to help improve the lives of black Americans while he was President. Instead of talking about those awful carpetbaggers, you instead see some positive stories about Reconstruction and how the reformers tried, but ultimately failed (until the mid 20th century that is), to give black Southerners the rights they deserved. Grant has risen quite a lot in some lists of Presidents as well, as a result, and the corrupt deal the Republicans made in 1876 (where they decided to abandon Reconstruction in return for getting the presidency again that year) is not a good moment; more progress could have been made had reconstruction continued.
While that view is still out there, it's a very good thing that Civil War history has moved beyond almost exclusively following the traditional Southern-led view on things that it always used to.