I don't get shown female interest very much, but when it happens I always second guess if it was real interest or just friendly banter.

Example 1: Work at a casino. 45yo 7/10 married MILF who's had a few wines wins 240 free spins on slot machine. I heard about it so I go down to chat with her. She's alone at the machine and I approach talking about the spins. She's excited watching the spins go. Turns to me and runs her two fingers down my chest looking right at me. I break eye contact not knowing what to do. End the conversation in a friendly not sexual manner at all and just walk away. See her days/weeks later while she's more sober and there's nothing.

Example 2: Same casino, different MILF woman who wins $5,000. I'm paying her with my older female supervisor standing beside me. It's standard procedure to ask for her phone number when the win is a certain amount. Right in front of my supervisor she asks me if I'm going to call her and mentions to me that she lives close by (when nothing in our conversation would have warranted asking her where she lived at all). I just smile and chuckle while my supervisor says "Oh so-and-so is such a kidder".

In my older days I had a habit of being so naive I thought innocent, friendly exchanges were signs of sexual interest and it backfired big time. Now I guess I'm afraid I'll think something is genuine, escalate to only find out it was not what I thought it was at all.

I guess there is no way to know if it's guaranteed, but is there a better way to approach these situations to gauge authenticity while having plausible deniability and face saving?