Funny thing about weathering (I do it, certainly, or paint entire project steamers or project diesel running gear in a "weathered black" for a certain quick-and-easy weathered effect): many go all ballistic over it (why?), but when I put a weathered piece of rolling stock on a sale table at a train show, it is almost always the first to get comments and the first to be sold. On our (now defunct) modular layout my dirtied-up locos always drew the most compliments and "crowds". Even a minimalist approach - like the running gear on a clean, early-career steamlined Dreyfuss Hudson - is correct and enhancing.
I haven't tried to sell a weathered loco yet, but I imagine that the response will be favorable, too. If ever.
Weathering - decently done, of course - is not "messing up a paint job"; it is part of the paint job. I should do it more.