  Room temperature ferromagnetic hysteresis is observed in commercial SrTiO$_3$
substrates purchased from a variety of suppliers. It is shown that the
ferromagnetic signal comes from the unpolished surfaces. Surface impurity
phases cannot be detected using either x-ray diffraction or energy dispersive
x-ray spectra on the unpolished surfaces. However, a possible correlation
between surface disorder (xray diffraction peak linewidth) and ferromagnetism
is observed. Ar ion bombardment (10keV-90 keV) can be used to produce surface
layer disorder but is not found to induce ferromagnetism. Annealing of the
substrates at temperatures ranging from 600 to 1100 $^\circ$C is found to alter
the hysteresis curves differently depending on whether the annealing is
performed in air or in vacuum. Identical annealing behaviour is observed if the
substrates are artificially spiked with iron. This suggests that the
ferromagnetic hysteresis of as purchased SrTiO$_3$ could be due to Fe
contamination of the unpolished surfaces. In addition, it is shown that no
ferromagnetism is observed in samples that contain $10^{19}-10^{21}$ cm$^{-3}$
of oxygen vacancies if all the faces are polished.
