@Eisengoth
I agree with this. I have been a reviewer for years and it's an odd book indeed that I don't find SOME error in. (Usually a missing/extra word in a sentence rather than a misspelling.) And that includes mainstream books. I don't get upset about it -- it's life.
The Amish supposedly leave an error in "on purpose" with each quilt because only God is perfect. (Of course, this is the excuse we quilters give when we see an error -- "I left that in on purpose.") I sort of feel the same way about books.