I was only really talking about this example (I didn’t actually read the rest until now 
):
あたしは ゼッテー汚れた金は 使わないのが主義なんだ
That seems to be a clear example of nesting to me:
As for me ◯
enter the nested sub-clause in the circle
As for dirty money ◯
now push down to the actual subject clause in this circle
I have a strict rule to never use [it].
I think the dotted line thing may be able to make this clear in a diagram. I’m still working on how to visually represent it clearly.
I think I understand the point you’re making. In particular, your point that も is inclusive while は is contrasting/disambiguating/specifying is a good one.
My (possibly incorrect) understanding of the grammatical term “topic” is that it’s basically context. The over-simplified English loose-equivalent might be “as for ◯, …” where the circle marks a topic.
So I’m not sure I agree that all your examples aren’t topics as I understand them:
As for [being] in Venice, …
The topic is “in Venice”.
As for the rumor about him, …
The topic is “the rumor about him”.
(Please correct me if I’m misreading any of this.)
Fortunately, I’ve talked to the mods, and they’ve marked this thread as non-mandatory for participation.
I’ve written elsewhere about experts like yourself sometimes not being the best teachers. This is a thread for (and by) beginners trying to feel their way forward. Like it or not, over-simplifications are a time-honored and proven form of pedagogy.
You may enjoy this thread that I linked to in the OP much more than this one.