"Cheating" implies a certain level of dishonesty. I think what most ladies are trying to say is that when a SO is aware of her occupation and has no problem with it, there is no 'cheating' because there is open and honest communication as opposed to any lying or deception. If, however no money is exchanged, that is when the fine line is crossed between business and cheating.
Longer to respond specifically to your point that having any kind of sex is cheating, you couldn't possibly be more wrong. It is more accurate to say that if *your* SO has sex with anyone else - male or female - that is cheating, period. And there is nothing wrong with that. Presumably your relationship expectation is that you will each remain monogamous to one another, and failure on either part to do is cheating. Nothing at all wrong with that. Most people would agree with that sentiment.
However, not all of us are wired that way. I've always sucked at relationships because monogamy is quite simply, something I have no interest in. The majority of my relationships generally entailed some amount of swinging, and my SO's were all perfectly OK with that. To be honest, if an SO wasn't ok with swinging, our relationship tended to be very short lived. This is one of the reasons why I believe I am perfectly suited to escorting. I simply love variety, and no matter how much I care for a man, the desire for variety doesn't change. So does that make me a cheater? I don't believe so. Never once have I snuck around behind a man's back to fool around with someone else without his knowledge.
Furthermore, since I am the one that prefers this lifestyle, am I being used if my SO (I do not have one, and am not really interested in finding one at the moment) is aware that I am a provider and is ok with it? Is he using me if we attend swing parties together? Again, I don't think so since I was a swinger for many years, have now escorted for many years, and don't need a relationship to love what I do and continue doing it.
Longer your beliefs probably hold true for the majority of the population, but we aren't all wired to place a premium on monogamy, or view a lack of monogamy as a negative.
Equation: You seem to be surprised by the idea that even though we enjoyed our time with you, it is still only business in our eyes. Well, for 90% of the population just doing business is a negative not a positive. No one wakes up in the morning eager and excited to go to work. Or at least, very few among us do. That is the joy of this occupation though. I love my business. When I have to take time away, like last month when I went out of town for a week to welcome my sister home from Iraq, after a few days I couldn't WAIT to get home and get back to work. So yes, it is just business. But that doesn't mean we can't love what we do