I usually tell people that I don’t answer open-ended questions (especially for anonymous callers). I do that by saying “I only answer yes or no questions”. This prevents a lot of issues. As a reference, you are there to assure the other person they are not going out with an axe murderer, and are basically what they say they are in the resume. Don’t talk too much.
This goes into the category of questions you automatically say yes to unless it’s an outright lie. Yes, this girl is tzniusdig. She may not be to your standards, but she has some tznius. They didn’t ask you if she dresses like a BY girl.
It’s like when you’re asked if a girl is smart or pretty. You just say yes. Because all that counts is what the boy she is dating thinks. If he thinks she is tzanua, smart, and pretty, then great.