  The location of surface brightness maxima (e.g. apocentre and pericentre
glow) in eccentric debris discs are often used to infer the underlying orbits
of the dust and planetesimals that comprise the disc. However, there is a
misconception that eccentric discs have higher surface densities at apocentre
and thus necessarily exhibit apocentre glow at long wavelengths. This arises
from the expectation that the slower velocities at apocentre lead to a "pile
up'" of dust, which fails to account for the greater area over which dust is
spread at apocentre. Instead we show with theory and by modelling three
different regimes that the morphology and surface brightness distributions of
face-on debris discs are strongly dependent on their eccentricity profile (i.e.
whether this is constant, rising or falling with distance). We demonstrate that
at shorter wavelengths the classical pericentre glow effect remains true,
whereas at longer wavelengths discs can either demonstrate apocentre glow or
pericentre glow. We additionally show that at long wavelengths the same disc
morphology can produce either apocentre glow or pericentre glow depending on
the observational resolution. Finally, we show that the classical approach of
interpreting eccentric debris discs using line densities is only valid under an
extremely limited set of circumstances, which are unlikely to be met as debris
disc observations become increasingly better resolved.
