I'm not sure what the issue was. There was obviously some fucking going on, but that really seemed to be amongst a small minority of guys. I did end up going into a cabin with maybe three different guys over the course of the afternoon, but when I asked not one of them wanted to fuck - or even cum! It was a very strange experience, and not one that I'm in any hurry to repeat.
Strange, I've wanted to go to a CumUnion even for the longest time, thinking it would be wall to wall raw fucking with guys shooting their hot cum up any arses they could find, but no, it was just like any other regular sauna day - they even shut an hour early, presumably cos it was so quiet - by 6pm there were probably around 8 guys in the entire place.