I thought I'd resurrect this topic because last night I performed "I Like Trucking" from Not the Nine O'Clock News. It's probably a good example of why comedy songs don't often sell. It works pretty well as a stand-alone song in my opinion, but it was really the video that made it - people remember the squashed hedgehog or Pamela Stephenson fondling the gearstick rather than the song itself. Which is a pity, because there are some quite clever lyrics and it's surprisingly interesting musically - it took me longer to learn than I expected.
A couple of weeks ago I performed another comedy song from the same era that did have some commercial success, and coincidentally also from a TV programme, Spitting Image. It was "The Chicken Song", written as a deliberate parody of those irritating holiday disco songs like "Agadoo" by Black Lace. Ironically, it ended up at number 1 for three weeks while "Agadoo" was only able to reach number 2! Not sure why it did so well - everyone hated it at the time, but then you were meant to hate it, so I suppose it was a self-fulfilling prophecy.