If someone is hostile or antagonistic, I walk. But generally I let the Holy Spirit speak to me, and even if someone is nice, I will know where their heart lies. I have been sitting at a table with
2 or 3 people claiming to be Christians and yet sensed a definite
quenching of the Spirit. It just depends.
At the same time, I have witnessed to one who said we should only bellieve in ourselves, and there is no God, because the condition of the world was so terrible. But the Holy Spirit said keep talking and at least by the time I was done, that person said, "God does love you." To which, my response was "He loves you, too." And it was time to stop.
We are to plant the seed, as you know, and God will take it from
there, as you know. God will either send someone or me or you
to water and next to harvest if the ground is right.
I love the way God works. He takes all the pressure off. He always knows what is needed next.