I have been to Mae's four times now and each time I had a happy ending. Three out of the four, were for free but the fourth and most recent visit, I had to pay an extra $40. Maybe they started to catch on
The first two massages were with Chanpen (not sure on the spelling), it is definitely ymmv with her as she seems to be somewhat picky. Be clean, nicely trimmed/shaved down there and respectful to her, and your chances of getting one rubbed out will be good.
The third was Majen (again not sure on spelling), she was very fun but does not work there anymore. Not sure why she left or if she was let go. She was not as good of a masseuse as Chanpen but she gave a better "Finish" to the massage.
Finally the fourth and most recent massage I had was good but not as good as the first two ladies. I can't remember her name but she is a bit older and only works part time. She was very nice and polite as the other ladies, but she kinda had a different vibe than the others. Still she provided a good service even though I had to pay an extra $40 for a finish.
Final thoughts, be clean, respectful and keep your area neat and you will have a good chance at getting your happy ending.