The History of Hygiene in Tamriel, vol. III 3E 223, Histarcapus Rochemont
Along the southern edge of the Heir'ach lies the famous Wrothgarian mountain range, named Altbal by the Bretons and people who live there. It also considered to be a Holy Land of sorts, one that has been fought over for millenia.
This is because many ages ago, the orsimer settled there, for it said that their god and creator Malacath saw the potential in the star-bound natural fortress of the Rock, which has led to much conflict. Even to the point that many people forgot what the fighting even started over, with a few of the scholarly dedicating time to "educating" those peoples for whom this has happened. For many, the reason for conflict with the orcs, is much to do with more recent atrocities, than religious and mythpoeic significance.
While savage and oftentimes lazy, the orcs have still managed to industriously pioneer in certain areas, and both Bretons and orcs have borrowed many cultural inventions from each other. Orcs for their smithing, and early on in Heir'ach history, advances in alchemy, and the smelly orcs in return have copied combat techniques, amateur magic in some cases, and other rudimentary tasks that they are often ill capable of. Though there are inferior in nearly all ways to man and mer, we do have one thing to thank them for, and that is improved hygiene.
Though it may appear that they have a prohibition on bathing, the orcs may possibly be credited with being the first in Tamriel to use soap. The story goes that a plague sent by Peryite was sweeping throughout the Rock as well as the lowlands, and many people were dying of sickness.
Though the orc casualties were slim in comparison to the Bretons, no doubt owing to their hulking figures and strong constitutions, the damage was still great enough to threaten them. You see, the savages are constantly in need of every individual in order to survive constant warfare, inner fighting, and turmoil. As a ruthless people in constant peril, they can never afford to be too outnumbered.
A medicine woman, Atub gra-Agrol, supposedly took the alchemically converted venom of their centipedes, and made a kind of disease-killing toxin, that at first was rubbed into open wounds. Surprisingly, this only had small number of casualties (leave it to a brainless orc to try the most unsafe application first), and they eventually mixed it in with various other substances, as well as animal fat from creatures such as deer and preferably troll, it became a salve of some kind. Of course it is not hard to see that it is almost insulting to compare this to the modern soap that we Bretons use! In any case, during the plague in the early second era, the orcs began rubbing this salve all over themselves, mixing it in their war paint, and even washing themselves in water. Because of this, they managed to become stronger than the surrounding area for the first time in Tamrielic history, at least until Heir'ach had recovered from the plague.
It was not until a few centuries later that we find the first Breton equivalent. Their salve was taken as a trophy during one of the many, many attacks on Orsinium. The Breton who rubbed it on his skin, unfortunately, couldn't handle the toxins, and died a slow death over a period of three days while foaming at the mouth. Interest did not wane however, and alchemists teamed up to discover how the stuff worked, and as you no doubt know, the result of their experiments was the modern soap. Innovations have been made in the past centuries however, and we now no longer use troll fat as the base, but sload fat, which is much more malleable and holds its form better, allowing the soap to last longer. This was a very needed enhancement, as the troll fat has an intense smell, especially when untreated, and often made the user smell just as bad in exchange for the cleanliness it provided, causing nobles to spend a fortune on bug musk, but I digress.
Before I leave off here, it should be noted that the Altmer and Ayleids both were documented as taking "sun baths" and using some form of magical art in order to cleanse themselves, and the dunmer used a special kind of ash mixed with Sload oil (them slugs seem to be everywhere huh?) sanctified by the temple, but generally only on religious occasions. This may be the reason that orcs of all things, were the ones to come up with the concept first, albeit primitive and unwholesome in many ways. Of course, it was man who finally made the genuine article, pinnacle of all hygiene, and it was of course the most sophisticated of man, Bretons, who saw it happen.