Well, In 40 years of marine flushing...
.... I have only had clogs that didn't self-clear a couple of times. Twice, despite instructions, guests tried to flush paper towels. In another case, a kid old enough to know better put something which I have forgotten down the head. That's all I can recall, other than pump failure a couple of times. Hardly worth getting worked up about. My wife does prefer the zip bag for TP for guests; I have no such rule and find if I simply instruct them how much to use and urge them to flush thoroughly between uses, I don't have a problem.