The boolProp cheat doesn't work. What does work is just 'testingCheatsEnabled true'.
You can change all five traits of the selected Sim. And you can slide their bars fully into the green  
Makes it a lot easier to 'discover' ... if you like cheating that is...
In the Sims 2, you could only slide the bars into the green when you went in and out the house/back to neighbourhood,
after using boolProp.
Now you can add the cheat directly and it works immediately!
What was possible in the Sims 2 and not in the Sims 3 is that you can't slide their skills, unfortunally...
but you can slide the friendshipbars into green also  

PS: second option of the cheat is to "go to the next lifecycle". Didn't used that option yet. You can choose to do that with visitors too.
But don't want to mess up my game at this stage! LOL!