I have heard of one provider that feels that her clients are hers and doesn't want to know of anyone else seeing them. And gets upset if she sees them flirting with or talking to other providers.
But this is a business and guys can see who they want, and when they want. If I'm asked for a reference I'm willing to give it, with no questions asked.
I know I like my variety in partners, why should I limit my clients' desire for variety by badmouthing them or being rude if I'm asked for a reference. But I've never been accused of being rude - but a couple close friends say I'm too nice.
I don't care what kind of a day the person is having, being rude is uncalled for.
Granted sometimes I may not be online for a day or 2 if I'm busy with family & don't have my hobby phone on or pay attention to email, but I will respond when I can. But I usually start my reply with an apology if it's been a couple days since they asked. I do check email frequently so that is the best way to get a reply quickly.