Ask them if they have experienced and increase in heterosexual arousal since beginning reparative therapy. There is no evidence that they do, even at the NARTH site.
Are you serious?
1. There was no "reparative therapy" involved. Read 1 Corinthians 6:9-11.
2. I don't know what you talk to your friends about, but I don't ask about any intimate sex details that they aren't willing to tell me of their own volition.