  We investigate the distribution of Blue Straggler stars in the field of three
open star clusters. The main purpose is to highlight the crucial role played by
general Galactic disk fore-/back-ground field stars, which are often located in
the same region of the Color Magnitude Diagram as Blue Straggler stars. We
analyze photometry taken from the literature of 3 open clusters of
intermediate/old age rich in Blue Straggler stars, and which are projected in
the direction of the Perseus arm, and study their spatial distribution and the
Color Magnitude Diagram. As expected, we find that a large portion of the Blue
Straggler population in these clusters are simply young field stars belonging
to the spiral arm. This result has important consequences on the theories of
the formation and statistics of Blue Straggler stars in different population
environments: open clusters, globular clusters or dwarf galaxies. As previously
emphasized by many authors, a detailed membership analysis is mandatory before
comparing the Blue Straggler population in star clusters against theoretical
models. Moreover, these sequences of young field stars (blue plumes) are
potentially powerful tracers of Galactic structure which require further
consideration.
