Worse: they could say yes, but poison the referral, ruining your chances with someone that (if you had gotten a different referral) would have invested.
I don't suppose that this effect is large, but it might be noticeable.
Don't think anyone would poison a referral? If someone wasn't impressed by you, they might agree to the referral anyway -- perhaps thinking they are being nice -- but when they tell the third party about you, they say "yeah, this guy didn't impress me, but I promised him I would refer him to you."
