[theme-reviewers] how close is too close?

[Amy Hendrix]

Hi all,

I'd love to see some discussion on themes that are obviously derived
from another theme, but have more new work in them than something
that's just a straight-up child theme. What's "too close"? Is it a
matter of adding or removing functionality? Rewriting significant
parts of template files (as opposed to, say, copy-pasting the new
theme name wherever the old one appears)?

At this point, I feel like there's a continuum that goes something like:

Author copied Twenty Ten but changed the site title to pink. Child
theme, also poor taste.
Author copied Twenty Ten, changed the site title to pink, and removed
the headers that say "Twenty Ten".
...
...
...
...
Author wrote every line from scratch. Author is an utter masochist who
never heard of code re-use.

And I'm clear on recognizing the ends of the spectrum but the middle
is fuzzy - so I'd love some thoughts from the rest of you about how
you recognize the line?

Thanks,
Amy