It seem to me not that she thinks that they cannot be virtuous etc, but that she does not give her charity contingent on their being so. She is very realistic and clearsighted in her understanding of their lives. To me this is a particular attitude in giving charity which belongs to the georgians and was replaced in the victorian age with much more conditional giving (by which I do not mean everyone in either age felt the same, just that there can be an overall approach to a subject which changes over time). It also suggests that the cottagers are too far removed from her circle for her to feel any need to draw out the distinctions between herself and them - unlike the Martins.

This passage was the first one where I actually liked Emma.