From the definition above, rust is oxidation. I think it's the quantity of the rust that goes from a nice 'patina' to "looks like junk!"
Years ago I did a watercolor of a Ford (blue) tractor, rusing in a field. The rust with the blue made it the perfect patina for painting. You can also see rust looking artistic on some of the photos on the 'another old truck' thread in the non-petro section.
Most of the patina folks here are referring to is a wear pattern on edges, or fading or slight change of color. 'Minty' (I think) would be something with just enough wear patina to show it was used, but the colors are still strong and there is minimal or no rust.
So IMHO there is 'good' patina and 'too much' patina. It's what every you like to look at. I, for example, like copper on a building with some patina (not shiny) but don't like it completely the livid whitish green it eventually becomes.
