An analysis of the polarimetric scattering properties of oil-covered waters is conducted using the classic Poincaré ellipticity parameter chi (χ) and the degree of polarization (m) from the Stokes parameters of hybrid polarized mode synthetic aperture radar (SAR). Oil spills reduce m for all four cases considered in this study. However, for the natural oil seep case considered, χ has a change in signs, comparing oil-covered waters with the “clean” ocean surface. The χ sign reversal is basic for “sign difference oil spill detection methods.” However, a problem is that the oil spill related to the deep water horizon (DWH) disaster did not exhibit a reversal in χ signs, comparing the “clean” ocean surface to the area contaminated by crude oil. The scattering mechanism related to the oil seep is different from that of the DWH oil spill; the former is dominated with even bounce scattering and the latter is dominated by Bragg scattering, similar to that of the clean oil-free ocean surface, in the imaging area.