The humor in this sketch is meant to criticize academics and literati who elevate the prosaic and the talentless for their own deluded reasons. The poet McTeagle goes about his life inquiring for money and going about his business in a very routine way, but some see his unspectacular "poetry" as works of art.
Factor in a grotesque critique of the Scots and herein lies the comedy. I've always enjoyed this one, especially after having watched or observed the latest art piece or film that the critics love but that I fail to understand. The elements of rape for comedic effect probably would not be included now, but the sketch itself is now over forty years old.