Steel - scratches/rusting

[OakLeaf]

You need to keep the seat tube dry regardless of the material - the point is to keep water out of your bottom bracket.

I suppose cromoly steel would rust if you really abused it - it doesn't have as much chromium as stainless - but it's not a cast iron skillet or a carbon steel knife. I've had chips in steel frames that I haven't been super careful of, but I've never had rust [touch wood].

I think if a bike sings to you, that's as good a definition of "it fits" as anything.