A sweep must involve one or more paths. These paths are always wire solids and if multiple paths are involved, the paths should touch at endpoints.
Note that the location of the paths is irrelevant to the location of the resulting sweep. The location of profiles control this. However, the orientation of the path is important in determining which end of the path is placed at the center of the profile during the sweep. If the default behavior is not desirable, simply change the Reverse Path parameter.