Those are value judgements not descriptions of the physical world that science tends to concern itself with.
In general I agree with the statement that eating excrement is bad, but I also recognise it has a social context. It assumes that excrement can be harmful and that humans should avoid harm, as well as that excrement dirty and that we should avoid impurity.
However it is funny you should bring up this example because I am actually considering undergoing a relatively new medical treatment known as a fecal transplant for a medical condition that I have. This essentially involves eating excrement. It is not ingested through the mouth but rather through a tube down the nose directly into the stomach. This method of insertion, as I understand it, is to avoid queasyness rather than hygiene, as it is ending up in the stomach anyway after all.
So for some people, in certain circumstances, it may be good to eat excrement.
But as I say, these are not the sort of statements that science generally concerns itself with anyway.