A strong indicator that someone is safe to interact with: They know how to say no. Because when they can say no, with ease and congruence: Then they can say yes, in the same way.
Dangerous interactions are the ones where people apologise a hundred times for saying no. People that take up an apologetic stance, and wants to ensure that their no is ok with you.
To say yes freely requires being able to say no, freely.
I enjoy a clear no.
That allows me to trust a clear yes.