It depends on the jurisdiction.  Most of the Recorders in counties I've worked in don't mind.  Others, like Wayne County in northeast PA, have signs posted prohibiting the use of any kind of image capturing equipment, scanners, digital cameras, etc. in their offices.

You could "test the waters" and try taking a few snaps of some docs just to see if anyone says anything.  After all, it's just as easy to ask forgiveness as it is to ask permission.

Regards,
Scott Perry