ORIGINAL: IFLY3W
Just by looking from the ass of the airplane, you can't tell 1 degree difference, and I've got pretty good eyes.
It actually doesn't take real good eyes, but with some experience and knowing how to look and where to look from and how to shift the plane makes it pretty easy to spot even less than 1.
But good thing about our hobby is there is more than one way to do most tasks. If you can't do it one way, there almost always is at least one other way, and using tools often doesn't take a lot of learning.
BTW, if it still carries slight trim in it, there is something the tools missed.