Q. How would it be best to punctuate spoken dialogue when a word is repeated to change or clarify meaning? For example: I “like” like you. (Alternatively: I like-like you.) Meaning: I am romantically attracted to you.
A. You are referring to the phenomenon known as contrastive focus reduplication (or simply contrastive reduplication), a term coined by Jila Ghomeshi, Ray Jackendoff, Nicole Rosen, and Kevin Russell; see “Contrastive Focus Reduplication in English (The Salad-Salad Paper),” Natural Language & Linguistic Theory 22 (2004): 307–57.
Ghomeshi et al.’s paper describes the effect of this repetition as “denoting the prototypical instance of the reduplicated lexical expression” (p. 308). In other words, it’s like adding “really” or “real” before the repeated verb or noun: I don’t just like you, I really like you. To illustrate the phenomenon, the text of Ghomeshi et al.’s paper uses an en dash between repeated words and, for repeated phrases, hyphens in addition to the en dash; to show the emphasis typical of such expressions, the first term is in all caps:
I’ll make the tuna salad, and you make the SALAD–salad.
Oh, we’re not LIVING-TOGETHER–living-together. (p. 308)
CMOS does not yet weigh in on this phenomenon, but we would probably say that in ordinary prose the dashes and hyphens are unnecessary. The capital letters provide a helpful cue, but italics, which are a little less emphatic, would be more appropriate in most situations. Here’s what that would look like:
I don’t simply like you, I like you like you.
Your idea of using quotation marks for the first term is a good one, especially when italics are not an option and when ALL CAPS or SMALL CAPS would feel like too much. But quotation marks might be read as scare quotes, making them more appropriate for irony than for emphasis.
In sum, Ghomeshi et al.’s approach works well in an academic paper on contrastive reduplication. But in a novel or a story or an ordinary piece of journalism, italics alone should suffice. Anything more than that would be overkill—as in, like, overkill overkill.