Not to sound like a huge douche, but I've seen my fair share of vaginas, and to be honest, there's so much natural variation among cis women (and trans guys!) that's I can't imagine how someone /could/ clock you? Unless it was from scars or something.
I mean, I totally get the anxiety about it, but if I met a dude who said he could spot the difference, I'd basically assume he was copping to inexperience. Or maybe being REALLY well versed in neo-vaginas. Idk. Anyway, I guess now I'm kind of curious about people's experiences.