I find that in gay personals ads (and I’m guessing straight ones too), there is often some confusion or disagreement about what the term ‘role play’ refers to, because it’s used in two quite different senses. When a boy tells he’s into role play, I always have to ask him what he means by the term, to make sure that we’re communicating clearly. In that sense, it’s like the term ‘slave’–it means multiple things.
One way that people use ‘role play’ is to refer to a type of scene play where the dom and sub pretend to be people they’re not–the dom is a cop and the sub is a criminal he catches, the dom is a burglar and the sub is the unlucky homeowner he ties up and molests, or whatever the scenario is. The fictional scenario adds spice to the scene and allows them to play with things like non-consent and abuse within a negotiated scene. In this sense, the dom and sub are not being their real selves because they are only faking being cop and criminal or whatever, even if they are being real doms and subs.
But there’s another meaning you run into in ads. In that sense, ‘role play’ refers to being ‘in role’ as dom and sub. The dom and sub are actively engaging in their power exchange, with the dom giving orders and the sub obeying them. This sense of the term signals the concept of ‘bedroom bdsm’, in which dom and sub don’t engage in full-time power exchange but only do so for set scenes. Thus they distinguish being ‘in-role’ from the more vanilla, egalitarian parts of their relationship. In this sense, the dom and sub are being their real selves when they in the scene.
Both definitions make sense and both are valid ways of describing kinky activities. So it’s not that one is right and the other is wrong. But it does mean that when you run into the term on dating profiles or the like, you need to be aware that the phrase doesn’t always mean what you think it means (regardless of which meaning you think it holds) and that you may need to have a conversion to clarify what you’re both picturing.