I mostly agree with your observation regarding CVs and what seeing this in one tells about the person who wrote it. Although I like to think that most proficient C++ programmers respect the differences between the two languages and prefer to call C++ what it is, and mention C separately if it needs to be mentioned.

I don't think the style of your code should change the name of the language you claim to use. If it doesn't pass through a C compiler, it's not C or "C/anything".

Now it is quite possible to use the subsets of C and C++ to write code that conforms to both language specifications and compiles with a compiler for either language. If some project deliberately does this, I don't have an issue with calling it C/C++ to hilight the fact. This however really is quite rare from what I've seen, even if I can name some projects that do make such code (the Opus audio codec is one example).

C/C++ still isn't a language though, so I would very much prefer to call it C in a case like this.

A different scenario entirely would be a project with parts clearly written in two (or more) different languages, which could happen to be C and C++...