As some might recall, Bart Brassica, has a colourised shadow (see The Oddity of Bart's Colourised Shadow). The  reason for this might, or might not, be made clear in a future episode. Of course, as any student of science knows, for every effect there is an equal and opposite effect, and in relation to Bart  Brassica , the colouric upkeep for his coloured shadow seems to sap certain places he visits of all grades of colour, leaving them like old black and white episodes of I Love Lucy ( except, mores the pity, that Lucille Ball does not appear). 
Here we see a rare photo of the back of Bart surveying what he calls Can Heaven, otherwise known as the Grocery Department in in the Lambertville Emporium, drained of all colour. All the store keepers are thoroughly sick of this effect and it is likely he will be escorted out.

PS Bart most usually avoids having his back to people or cameras, being touchh about the embossing on every single one of his shirts.