If you all you could see were their penis or pussy, could you pick your partner out of a line up? No looking at photos for reference, just from memory. Would they need to be hard/aroused for you to recognize them? What about previous partners?
I think I probably could pick out my partner’s pussy both aroused and not. The way her labia sit is very distinctive. I doubt I could still recognize previous partners, maybe I could when we were dating.

Could I recognize my own?
I think I could recognize my cock in a list of 20 random ones but in a 100 I might get it wrong. No chance I pick my gfs pussy in a lineup of 10 :D. If it showed the surrounding areas then maaybe