Clean or Dirty?

When I put my Pashley Princess up for sale last week, I had been planning to wash the bicycle before showing her to potential buyers. But things happened fast, and the Princess was purchased just as she was. And the surprising thing is, she looked absolutely clean even without having undergone a washing. Examining the shiny frame with just a few specks of dust here and there, you would never know that this bicycle had seen a year of use, including having lived through a New England winter. Not only were there no scratches on the finish, but there were no mud stains either. I am not sure how exactly that's possible, but there it is. Is powdercoating not only durable, but somehow stain resistant? Seems unlikely.

In contrast, my poor Rivendell Sam Hillborne is absolutely filthy after less than 4 months of use. I will spare you the close-ups of the dirty parts, but he seems to attract mud and grime like honey attracts flies. I am not a person who washes their bicycles after every ride, and I never will be. And while I expected the exposed components on a roadbike to gather dirt, it never occurred to me that the very finish of a bicycle could be dirt-prone or dirt-resistant. The pretty liquid paint on the Rivendell is delicate compared to the thick powdercoat on bicycles like the Pashley and the Gazelle and it is much easier to nick. But does liquid coat also require more cleaning than powdercoat? That is not something I had ever heard before, so I am wondering about others' experience.

Do your bicycles seem to stay clean on their own, or do they require constant washing?  And while I do not mind the look of a dirty bicycle, I am wondering whether leaving the Rivendell like this for long can result in any sort of damage or corrosion? Your thoughts appreciated!