Despite the fact that this is a case where my expertise is directly pertinent to the question--I have written a history of hygiene, body image and consumer culture in 20th Century southern Africa--I hesitated a bit before undertaking an answer to this question.

The reason for my hesitation is that this overall topic has lately become a sort of strange eddy of conversation in social media, swirling off as a kind of fractured debate between white supremacists and Afrocentrists and Black cultural activists with scholarly historians from several different areas of specialization feeling helpless to wrestle the whole conversation back to something more factual.

At a deep anthropological level, practices of decorating, washing, marking and shaping the body have been a major part of how neighboring cultures differentiate themselves from one another--and as such, are often also part of how neighboring cultures denigrate or criticize one another, particularly using tropes around purity and uncleanliness. (Mary Douglas' famous book Purity and Danger provides a really good window into this level of cultural and social thought.)

In the post-1400 CE time period, however, this common discourse about cultural difference got very powerfully entangled with two things (which were themselves already connected): the sudden appearance of Europeans in many parts of the planet that they previously had not visited or related directly to and the rise of modern discourses of racial difference, hierarchy and domination.

There are some good examples in the early modern period in the era of "first contact" between Westerners and non-Western societies of commentary on or perceptions of the bodily habits and appearance of people on either side of those encounters. But especially between 1400 and 1600 CE, many of the views that we attribute to modern racism or racial ideology were not yet a standard or prominent part of those contacts, including uniformly negative characterizations of the cleanliness of the bodies of the other side of that cultural encounter.

It's only in the 19th and 20th Century that we really see white Europeans and Americans describing non-white individuals and societies with highly charged, racist images of dirtiness and filth, often combined with regarding them as a source of disease and contagion. These ideas were sometimes the justification for or logic of spatial segregation (e.g., forcing colonial subjects or racialized populations to live in separate communities far away from white populations, usually communities with minimal or absent infrastructure and support).

This is where things get really complicated in terms of the OP's question. Part of this evolution of the racialization of hygiene also included the creation among Europeans of a myth about their own past unhygienic behavior. Some of this wasn't mythological in the sense that early modern and late medieval European cities had relatively polluted water supplies or poor drainage and sewage, or lacked public bathing. Some of it was an exaggerated form of self-promotion originating from people backing projects of urban planning and infrastructure construction in European and American cities (e.g., look at us now! look at what we're building! we were so filthy before and now we're not!) What this led to was the building of an idea of medieval Europeans as anti-hygienic, as resisting bathing in water or wallowing in mud and filth. (Say, Monty Python's joke about knowing who the king is because he doesn't have shit all over him.) Some of this was also the specific by-product of Protestant critiques of medieval European society under the authority of the Catholic Church as corrupt, degenerate, and unclean and about the rise of humanism and its affection for Roman and Greek thought (and therefore also the material culture of Roman life, including the centrality of social bathing).

This all became such a powerful truism--that Europeans were markedly unclean compared to other global societies prior to 1900--that I have to confess with some embarrassment that I bought into it myself a bit when I first started working on this subject around 1990. And there are scraps of truth to it. As Virginia Smith point out in her 2007 history Clean, late medieval Europeans began to adopt new clothing fashions that included undergarments and tight-fitting tailoring, which in turn created new ways to "trap the body's evacuations in a layer above the skin", whereas many other societies in the Mediterranean, Near East, and Asia wore looser-fitting clothing and robes that made it easier to stay clean and smell less. There were also forms of body asceticism that circulated in Christian institutions or rituals where washing was avoided, but that appears in other religious traditions too in other parts of the world from time to time.

Many other common ideas--that spices and perfumes were desired to cover the odor of rotting meat and unwashed bodies, or that Europeans commonly had a cultural objection to washing or cleanliness, are basically untrue. But it is true, Smith notes, that Islamic communities around the Mediterranean, including in Iberia, specifically retained and extended Roman-inspired architecture for bathing and sanitation, and became known as a kind of ideal of cleanliness and courtly life throughout Europe as a result.

Which brings around again to the OP's idea, now echoed across social media, that Europeans had to be tutored in cleanliness by the Moors, by Muslims generally, by Africans, by Japanese, etc. This is essentially a further extension of the myths built by Renaissance, Enlightenment and modern Europeans about themselves, myths that built on some half-truths--and the extension in this case is intended to frame modern white racism about non-white hygiene and bodies as supreme hypocrisy, to flip the racial imagery on its head.

That's a very understandable objective. I have a lot of sympathy for the thought behind the move, not the least because there's a sort of truth down buried down in it. Not just in terms of the hygienic past of Europeans, but also in terms of how white European and Americans have used hygiene as an excuse for racial segregation and discrimination and how that remains a part of racist culture today. Throwing racist ideas back on their originators is a powerful strategem in many respects. It's also true that 19th and 20th Century whites reproducing those racist ideas created humiliating and degrading myths about the societies they were discriminating against. When I was interviewing people in Zimbabwe about soap, cosmetics and other products for the body, people were often palpably worried that I was operating from the preconception that local African cultures were (or had been) unclean, which I already knew was absolutely not the case, that precolonial bodily practices included frequent washing, the uses of natural oils to protect the body from dirt, and the use of soap-like botanica. Similarly, it's true that medieval Islamic courts and urban communities had infrastructure for bathing that many European communities lacked (and that many European courts admired). "Flipping the script" on modern bodily racism is in that sense even somewhat factual.

But not as much as is thought to be the case in some current social media discussions. Medieval kings were not the only ones who did not have shit on them; medieval Europeans did not wallow in mud or invariably crawl with lice. Medieval and early modern Europeans were just as interested in washing and remaining clean as human beings in any other past society.