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Recent studies have made the community aware of scattered light whenexamining low-surface-brightness galaxy features such as thick discs. In ourpast studies of the thick discs of edge-on galaxies in the Spitzer Survey ofStellar Structure in Galaxies (S$^4$G) we modelled the point spread function asa Gaussian. We re-examine our results using a revised point spread functionmodel that accounts for extended wings out to more than 2.5arcmin. We study the$3.6\mu{\rm m}$ images of 141 edge-on galaxies from the S$^4$G. We decomposethe surface brightness profiles of the galaxies perpendicular to theirmid-planes assuming that discs are made of two stellar discs in hydrostaticequilibrium. We decompose the axial surface brightness profiles of galaxies tomodel the central mass concentration - described by a S\'ersic function - andthe disc - described by a broken exponential disc. Our improved treatmentconfirms the ubiquity of thick discs. The main difference between our currentfits and those presented before is that now the scattered light from the thindisc dominates the surface brightness at levels below $\mu\sim26\,{\rmmag\,arcsec^{-2}}$. This does not affect drastically any of our previouslypresented results: 1) Thick discs are nearly ubiquitous. They are not anartefact caused by scattered light as has been suggested elsewhere. 2) Thickdiscs have masses comparable to those of thin discs in low-mass galaxies -circular velocities $v_{\rm c}<120\,{\rm km\,s^{-1}}$ - whereas they aretypically less massive than the thin discs in high-mass galaxies. 3) Thickdiscs and central mass concentrations seem to have formed at the same epochfrom a common material reservoir. 4) Roughly 60% of the up-bending breaks inface-on galaxies are caused by the superposition of a thin and a thick discwhere the scale-length of the latter is the largest. (Abridged)

The reports of thick discs' deaths are greatly exaggerated: thick discs are NOT artefacts caused by diffuse scattered light