I've never needed to clean the heating element in my MES, either. It glows orange when it's preheating, and that's better than a self-cleaning oven!
But if you were to get a coating of ash on the element, it probably would be best to wipe it off so it wouldn't insulate the element and perhaps cause it to overheat internally, leading to a premature failure.
But I've never noticed any ash residue on the heating element of my MES even after many years of abuse!
When coal is tested in the lab for "ash content", it is burned at a very high temperature, and any residue left is obviously non-combustible (basically inorganic material). Think of it as rock! That may melt, but not vaporize. The residue is difficult to remove and creates "clinkers" in the combustion chambers of power plants. So that's undesirable.
But I can't think of much source of inorganics in a smoker, but I could be wrong!
Have not unboxed yet, but my new Pit Boss manual says to clean the electric element every 5-6 smokes with a scrub pad and soapy water. I was surprised to see that, as I have never seemed to have to clean these elements on other units/stoves, and not easily detachable (like the old range cooktop elements were).
Is that a fully electric smoker, or is it one that burns the pellets to generate the heat as well as the smoke? I looked at a Pit Boss unit at a local store the other day, and it was a pellet burning smoker. The heat was generated by the burning of the pellets, but it had a small (200 Watt) heating element that is only used to ignite the pellets. Then a corkscrew gadget feeds the pellets into the combustion area and a blower stokes them, and the rate of pellet feed is adjusted by the temperature controller to maintain the temperature.
I guess I could see how some residue might accumulate on a small element that is only fired up to ignite the pellets.
But Pit Boss also sells "all electric" smokers that actually do have an electric heating element that heats the smoker. So without knowing what model smoker this is, it's kind of hard to know why they'd be advising you to clean the heating element.