How to tell if someone's a lesbian?

I’m 16, I’m a female.On an early morning, I was passing by some department stores.I use that route almost every time. Anyway, the lady in one of the department stores (make-up)caught my attention, and came closer. She wanted to apply make-up to my face and asked whether I would agree.I wasn’t so sure but I said,“OK.” She wanted to know where I was staying ,and I told her. Then, she asked me whether my mom will give permission.I told her I didn’t know but I could ask her. Finally, she asked me for my number and said she will call in a couple of minutes, to see what my mom’s decision was. I told my mom,but she said no. Later I showed a picture of the woman (Freeda) to my mom. she said she’s a lesbian, So there is no way she would allow me to meet up with her. l just want to know your opinions.Can you tell whether someone is a lesbian, just from looking at her picture?