No, plumbing isn't a bad thing. As I generic term I might use it myself. The porcellain part though moves it clearly to the toilet topic, and that part I find unfitting. And the original poster just didn't understand what was meant with the differentiation between the porcellain and the plumbing. Which caused me to comment that software authors should be a bit more carful when naming things. What starts as a inside joke might not be well understandable by outsiders and off-putting in the extreme cases. After all, naming is about being understood.