  We consider one-dimensional transport through an interacting region in series
with a point-like one-body scatterer. When the conductance of the interacting
region is perfect, independently of the interaction strength, a nonlocal
interaction effect yields a total conductance of the composed system that
depends on the interaction strength and is lower than the transmission of the
one-body scatterer. This qualitative nonlocal effect allows to probe the
dressing cloud of an interacting system by ideal noninteracting leads. The
conductance correction increases with the strength of the interaction and the
reflection of the one-body scatterer (attaining relative changes >50%), and
decreases with the distance between the interacting region and the one-body
scatterer. Scaling laws are obtained and possible experimental realizations are
suggested.
