I recently learned that the waltz was considered a very sexual dance when it first premiered and so that got me wondering: is Western music (and the culture around music, such as dancing) today actually significantly more sexual than what came before it as some people claim, and, if yes, is this a recent trend or something that has been slowly accumulating over years?
I feel like I'm always evangelizing this book, but I have been reading the Oxford History of Music by Richard Taruskin (2005). Going back at least to the Renaissance, some music was intended to be heard as, and apparently was heard as, having very sensual or sexual connotations.
There has always been sexualized music and dance. How appropriate this was considered for mixed company has varied by culture and period.
Translated Sumerian temple chants/songs for public celebrations made no bones about being fertility songs, using lines for the Goddess like "Who will plow my vulva?" Look up "lingam and yoni" for the religious use of genitalia in India, or huge representations of silk over frames, lit up from inside, in traditional Japanese festivals.
But I'm pretty sure what you want is the Western European tradition here.
The songs were out there, but rarely written down. Most music was rarely recorded until the sheet music industry arose. We do have risqué medieval songs from sources like Carmina Burana (11th-13th C) or the Cambridge Songs from around 1066. A fine lady might have been insulted to hear it, but the Wife of Bath probably knew all the verses.
So you have a tension down the centuries of those who like their bawdy songs and those who want something less sexual. This is usually the middle class. The peasants think sex is what life is about, and often so does the court. Consider the license of the English Restoration, and how much Restoration comedy relies on sexual misbehavior for its plots.
There also came Wit and Mirth: Or Pills to Purge Melancholy (normally called Pills to Purge Melancholy), a large collection of songs edited by Thomas d'Urfey, published between 1698 and 1720, which in its final, six-volume edition held over 1,000 songs and poems. They can all be called bawdy or ribald. They also often are very similar to others in the collection, and you get used to the continual use of certain euphemisms, like "the white of an egg ran down her leg" which has the virtue of being pre-rhymed. This was not art song: it was the low stuff from the taverns.
What you have at the end of the 1700s is the start of the development of what would be called Victorianism as the wealthy middle class begins its rule. You might want to look into Ben Wilson's The Making of Victorian Values: Decency and Dissent in Britain: 1789-1837; 2007; Penguin press, NY.
The important thing to note about the indecency of the waltz (popular in England from c.1815)(more like 1800 in Paris, and coming from Germany) is that it was the first dance since the Renaissance galliard where the dancers embraced each other, and for the first time continuously through the dance. Before then, all upper and middle class dances (and oft the galliard) had partners just touching hands with extended arms, and often changing partners down a set, the way in square dancing partners will momentarily dance with their corner or opposite. Before the waltz, the court dance was the minuet. The fashionable dance was the contredanse or country dance, which survives in Scottish country dancing.
A good book for bawdy songs in America is The Erotic Muse, now much encumbered with an historical timeline of headlines.