In our Pathfinder campaign, the party was doing shopping in the campaign’s version of Las Vegas, selling the loot from a recent dungeon and buying upgrades for ourselves.
The city is divided into five islands with airships that go between them, all run by different “families” or cartels.
Certain magical items we needed were only sold in the demon district, and we found ourselves in a small shop run by an imp succubus. She had what we were looking for, and offered a discount if one of us spent the night with her. Greater discount if more than one did. Alas we had plans for the following day and knew a night with her would leave us exhausted, so we had to decline. I settled for a kiss instead and she sold the item for a reasonable price.
Side note: We established no soul-trading, we would only deal in platinum, and perhaps essence (something we could recover with sleep).

The DM described her as a scaleless dragonborn with dark reddish skin and devilish horns, wearing nothing but a tiny loincloth that barely covered anything. I loved the mental image and just how saucy she was being with the party and had to draw her.