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We use mid-infrared Spitzer spectroscopy and far-infrared Herschel photometryfor a sample of twenty main sequence O9--B2 stars in the Small Magellanic Cloud(SMC) with strong 24 micron excesses to investigate the origin of the mid-IRemission. Either debris disks around the stars or illuminated patches of denseinterstellar medium (ISM) can cause such mid-IR emission. In a companion paper,Paper I, we use optical spectroscopy to show that it is unlikely for any ofthese sources to be classical Be stars or Herbig Ae/Be stars. We focus ouranalysis on debris disks and cirrus hot spots. We find three out of twentystars to be significantly extended in the mid-IR, establishing them as cirrushot spots. We then fit the IR spectral energy distributions to determine dusttemperatures and masses. We find the dust masses in the SMC stars to be largerthan for any known debris disks, although this evidence against the debris diskhypothesis is circumstantial. Finally, we created a local comparison sample ofbright mid-IR OB stars in the Milky Way (MW) by cross-matching the WISE andHipparcos catalogs. All such local stars in the appropriate luminosity rangethat can be unambiguously classified are young stars with optical emissionlines or are spatially resolved by WISE with sizes too large to be plausibledebris disk candidates. We conclude that the very strong mid-IR flux excessesare most likely explained as cirrus hot spots, although we cannot rigorouslyrule out that a small fraction of the sample is made up of debris disks ortransition disks. We present suggestive evidence that bow-shock heating aroundrunaway stars may be a contributing mechanism to the interstellar emission.These sources, interpreted as cirrus hot spots, offer a new localised probe ofdiffuse interstellar dust in a low metallicity environment. (Abridged)

Dusty OB stars in the Small Magellanic Cloud - II: Extragalactic Disks or Examples of the Pleiades Phenomenon?