I pretty much never listen to otome CDs during the day, whether they're R18 or not. To me, otome CDs are very much a nocturnal enjoyment -- when the sky/room is dark, all is quiet around me, and there are little to no distractions, it's much easier to "get in the mood" for a sexy story, haha. So yeah, I listen to them basically only before I sleep at night, and typically while lying in bed. I also don't listen to otome CDs AT ALL when I'm outside/commuting/on the go, because I reckon I'd get weirdly self-conscious about people "being able to hear" what I'm listening to, especially with a guy panting and moaning into my ears.

Plus it'd also be kind of hard for me to concentrate on the audio when outdoors, with all the inevitable noise and activity around.
I'm honestly quite surprised that some of you actually listen to otome CDs while gaming or doing household chores. I know I could never -- I need to focus 100% on listening to the CD.