Being new to all this, I can't disagree with that, but somehow I just can't envision cleaning 8 wheels on each car I'll eventually have in my inventory as often as I'll clean my track.
Well, first, I don't think you have to clean the wheels of rolling stock very often. Two reasons. First, electrical current flow has a good deal to do with how quickly dirt and grime accumulate. Wheels on unpowered cars don't get nearly as dirty. I've heard various reasons given as to why - I'm an electrical engineer and I have a pretty good idea myself but I figure it doesn't matter - they just do: wheels and rollers that have power go through them get dirty - those that don't, don't. I did an interesting experiment a few years ago: cleaned a three-roller loco well, then disconnected one center roller so current did not flow through it and ran the thing hard for a week or so: the two rollers that were still conducting power got gunky - but the disconnected one was pretty clean. So-you really only have to clean the wheels and rollers of locos and tenders and lighted passenger cars and cabooses.
Second, if a rolling stock has no power pick up and doesn't use electricity, you really don't care if its wheels are so dirty it won't conduct electricity.