I have no problem giving references to ladies that I know, but if I've never heard of someone and they come out of the blue asking me for a reference it immediately puts my guard up! That's why I tell my clients to contact me first so that I am expecting an email/call from a provider. Otherwise, I will never admit to knowing you or anything about you! This is for my safety, as well as yours. Suspicious and snooping significant others are never a joy to speak with on the phone, trust me.
Also, I do my homework and look the lady up online to find out what I can about her. If she has no website or reviews anywhere it really makes me nervous about whether or not she's "legit". (I know sometimes you guys don't always think with the big head lol)