I always thought it was charming that they kept Spike corpsing, shows it was obviously first-take stuff, and the audience is actually really reacting to him rather than being forced to laugh after 39 takes.
Spike just had funny bones. He didn't need to say anything to get a laugh. When he just wanders out of shot, bewildered, on his own in Life of Brian, it made me laugh. I wish the dancing in a dustbin song was longer! Xx