When you improvise on the spot, people are very reluctant to have soft moments or quiet moments or sad moments because they're trying to fill up the spaces. So they always go towards, "How come you're late?! You're supposed to have my shirt ready! You call this a dry cleaner?!" That's what happens. That's why improvising on the spot gets very dicey.
For the most part, improvising while cameras are rolling is very difficult. 99% of people you should never ask to do that, because they're under pressure, the clock is running, 80 people are staring at you...it's always unnatural.
