The polar caps of Mars, primarily composed of water ice with minor fractions of Martian dust, serve as a record of the planet’s past dynamics. Distinct dust-rich layers have been observed in exposed outcrops of both the North and South Polar Layered Deposits (NPLD and SPLD). Some of these layers correlate with bright, parallel reflectors detected by the orbital sounder SHAllow RADar (SHARAD) in the subsurface of both Martian polar caps. Some of the radargrams from high-latitude regions of the SPLD also include a pervasive elevated radar background either filling the spaces between layers or obscuring them entirely, usually referred to as “fog”. While most common explanations include off-nadir roughness or volume scattering, existing literature does not include quantitative attribution of this phenomenon. To address this, we measured backscattering and attenuation of fog from a few SHARAD tracks and compared these to the signatures of plausible subsurface interfaces. While volume scattering is too weak to explain fog, we find that specular reflections from dusty layers, when sufficiently thin, fragmented, or low in dust content, can account for both the observed backscattering and low attenuation of fog. This suggests that fog regions of the SPLD may host densely spaced weak reflectors resulting from the same kind of dust layers as the brighter slabs detected in the NPLD. As a result, the contrasting appearance of the northern and southern polar caps in SHARAD radargrams could be attributable to differing stratigraphic profiles rather than distinct scattering mechanisms.