Update from me. I went to S-Sense this evening to give it a go. I booked via Line. My masseur, Aek was lovely. Cuter in the flesh than in the pics, and friendly too.
I took a shower first (in the room) and we began. Even though I was face down, I noticed that he took his shirt off. He did a good quality massage. Then, he turned me over, "aroused" me (which wasn't difficult) and asked me if I wanted somthing or other. I didn't understand what he said, despite asking him to repeat it, so I asked how much this extra thing cost and he thought for a bit and said 900, so I said, "OK, sure", at which point he promptly took the rest of his clothes off and climbed on top of me for some cuddling, licking and wanking. All very nice.
He then showered, and returned to massage my legs for another 10-15 minutes until the 2 hours was up. I showered while he fetched some tea to the room. I wasn't sure if this 900 figure that I had aparantly agreed was in addition to the standard tip or not, so I offered him a 1000 baht note to gauge his reaction and he seemed very happy, so now I know. (Perhaps he had expected me to negotiate that 900 down a bit.)
So that was my first experience of S-Sense. Is that typically how things go in a place like that?