People see nothing but plastic back there, particularly when the seats are removed...and do retarded things. Who knows where the "spray out the back" wives tale started.

Still, it's far and away the easiest to clean interior of any vehicle I've owned. Shop vac, followed by diluted simple green and a sponge - done in 10 minutes.

All the plastic back there does get scratched easily, so if that's a concern - plenty of folks pick up those heavy rubber horse stall mats from Tractor Supply, and cut to fit. Supposedly, this also helps a tad with the interior noise as well.