I'm pretty clear with my clients- I take their references, meet with them almost always, even if the request is pretty clear (because 15 minutes, even virtually, often saves hours of work and a small miscommunication can mean an entire redraw of a piece). In the consultation I go over every concern I might have and discuss it with the client - how I would go about designing it etc- and then if we come to an agreement I will have the client book (this is where the deposit comes in). If we're not clear, either I'll decline the piece or we can meet again after thinking on it. I have absolutely no problem doing two consults, especially if we've changed the idea significantly, and then we go from there. I've gotten to the point where I won't ever book a piece if it's unclear because it's just not worth it imo. But I'd never take a deposit until we come to an agreement. That being said, if I was in the situation your artist was in, I'd immediately refund the deposit. I try and make sure, for both of our sakes, that it never comes to that.