My SIM always gets a „dissapointing Wohoo“ moodlet after wohooing with another SIM.
Both SIMs are on level 4, I remember an entry in the Journal-Book which says „Chance for dissapointing wohoo: 100%“

how do I change that? Is there a way to get a better chance?

First of all, just to clarify in case this is necessary, the satisfaction moodlets, strength, and duration that sims get from woohooing are dependent on the KS skill of the other sim. Not their own.

On the very lowest skill levels, the result will not always be postive. On Levels 2 through around 6, there should be a mixture of positives and negatives much of the time that should balance out to a net mood gain if considered all together. Woohoos off the home lot that trigger the away from home and Stride of Pride moodlets are highly positive and tend to overtake the slightly negative ones that don't last very long. At the higher levels, the chances for all postiive and longer lasting moodlets are much higher.

This will also depend on whom the sims have woohoo'ed with -- their ever-faithful life partner, vs. friends, total strangers, and/or working KS professionals and the sims' traits.

Note that it's not just the KS skill levels that dictate these, it's really the sims' Renown scores as can be seen on their skill tabs. KS skill is only one component of those, the scores will also increase with the eventual completion of the major and minor skill challenges. The major one that comes with 50 woohoos is huge and tends to overpower the chances of negative moodlets almost (but not always) entirely.

Many of us find the challenges that lower but still growing Renown scores bring to be satisfying to play through as long as our Level 2s and higher don't consistently give their partners ALL negative moodlets each and every time. But if you still want to tinker with the chances of satisfaction, the options should be there on NRaas > Woohooer > KamaSimtra (on City Hall or an in-game computer).

I solved it with one of my sims by giving him a logic level of 10, and an embarrassing tendency to use the resulting ability to train other sims in a skill by selecting his KS skill as the skill he trained. (Although I started keeping a closer eye on him when I realized that he was also happily lecturing teenagers... At least they are likely to be partnered up before they are old enough for him to get involved with them.)
 

That's one way to go about it, yes. I've also had sims deliver lectures on the topic using Uni's whiteboards, but getting an audience to stay still and pay attention is trickier than it probably should be. Although it was kind of funny when my vamp gained three skill points all at once, not sure if that was really due to vamps learning things more quickly or if the skill just doesn't work well that way. And there are KS skill books available from kimlupai at The Sims Asylum for those who would prefer to learn some the skill by reading rather than practicing on what could be unsuspecting partners.
http://simsasylum.com/tfm/index.php?/to ... ill-books/
(account and login required to see anything there)

But it's really the Renown score, of which the skill is only one component, that makes things happen with this one.

The podium seems to be the real jaw dropper here: Near instant level 10. This takes less than half a lecture. It's kind of ridiculous.

Of course, someone has to reach level 10 some other way first.

Turjan wrote: The podium seems to be the real jaw dropper here: Near instant level 10. This takes less than half a lecture. It's kind of ridiculous.

Of course, someone has to reach level 10 some other way first.

Yeah, I remember having some discussions with Chain and icarus_allsorts back when he was an active developer here about that. The issue is that the KS skill does not rise smoothly over time like most of the others do, it is meant to be notch based (one woohoo = one notch) so it doesn't respond to the lecture scenario in the same way that the others might. How the two popular series of skill book mods manage to pull off the skill gains more smoothly and gradually is still kind of an unanswered question.