Coffee Appreciation

Make a stovetop and leave it on the side in the kitchen for a week. That's the same shit breeding in the exhaust of your machine when you don't backflush it.

It's nice to know that any parts of the machine which have been in contact with coffee are totally clean when you walk up to make a shot. OK, it's on the exhaust side and shouldn't end up in your drink but knowing that there's perishable coffee muck sitting in those pipes at a nice cosy bacteria friendly temperature during warm-up and cool-down feels at odds to all the care you take at every other stage of preparation.

tl;dr It takes 1 minute and it's a bit skanky if you don't.

But I run the brew switch through the portafilter and grouphead (also semi-fitted and wiggling to get some water around the gasket) after each session.

If, after making the hypothetical stovetop, I ran ~boiling water through the emptied basket, spout, and reservoir, build up of bacteria would be negligible, and build up of unwanted oily patina would be retarded (no, not 'retarded' in that sense).