In my experience the client and providers comfort level in discussing the monetary transaction varies in regards to the type of encounter they are looking for/provide. A client that is interested in something shorter with clear cut boundaries, sex for money has no issue discussing the money, time limits, etc. A provider that has a menu of sexual services, set time limits, and keeps a specific schedule will also be fairly comfortable when it comes to discussing the cash transaction. A client that is booking for longer times, dinner dates, overnights, etc. where the time limit is flexible, where the environment is social and where one is getting to know the lady on a more personal level (not more intimate but it is more personal) often prefers to have the cash transaction dealt with in advance and not brought up again. The environment is social not business and as such it can ruin the mood to start talking about it. The same holds true for the ladies, those that focus on longer dates and social environments tend to prefer to not have a 'business transaction' mindset which means having the money aspect dealt with in advance so that when they are with the client it is a little more social. Now this is just a generalization and there are always exceptions to the rule; some clients enjoy discussing the "hobby" on their dates and others like a "date" feel but book short engagements for their own personal reasons.
As for myself, I prefer to not discuss it, I can only work in this industry when in a social mindset. Those saying that if you can't discuss the money you should get out of the business I disagree, in fact I think it's that disposition that sets me apart. I do not like to look at it as just a business transaction and I don't like to meet with others that view it as such as well, we generally don't click. I enjoy spending time with the people I meet and when it starts to feel too much like work, when I am in a business mindset then I cannot enjoy it and I am not at my best. When a new client asks me about rates I direct them to my site or as many have attested to they get a not as brief as it should be (sorry!) explanation of my 'flexible' time packages. After we've met a few times I'm comfortable discussing it but generally in the abstract much the same way that you talk about work with your friends, lovers, etc. I'm also upfront with my dates in letting them know that I don't like it to be a business transaction and that if they are looking for set times, rates and services then they should not see me.
There is a provider out there for everyone and finding the right one for you is what's important.