> IMSLP is great for finding quick scores of random stuff, but the editions are often pretty shoddy, like either super outdated with weird editorial decisions that no one's agreed with for the last 50 years, or someone's totally amateur transcription full of errors and equally weird decisions.
You picked my interest.
- what makes an "edition" ("score"?) outdated?
- can you give examples for a weird editorial decision, maybe by additionally providing an alternative good editorial version?
- what happened that something deemed correct (?) over 50 years ago is nowadays something no one agrees with?
In the last decades philological standards for reproducing the original form of a musical work taking into account historical musical traditions, composing and performance practices have become much more thorough. Editions from the 19th and early 20th century which you can find on IMSLP because they are out of copyright restrictions often don't meet these scholarly standards. They very often reflect performance practises and the style of their time. See also https://en.wikipedia.org/wiki/Urtext_edition.
I’d add that some of the older texts are really badly laid out - often handwritten or in a strange typeface that makes them really hard to mentally parse when you‘re used to the uniformity of modern scores.
That said imslp is still a life-saver and playing music would be a lot more painful (and expensive!) without it
To give an example to further illustrate answers you've received. In the 1800s it was common to produce heavily editorialized volumes of Bach, Scarlatti and other baroque keyboard works, with tempo and dynamic indications, written-out ornamentation, phrasing and articulation marks, pedalling, and other directions that would have been a relatively alien language in the actual autograph and early editions. These were much more reflective of (romantic) performance practices of the day than of the original period. While much of it could be taken as potentially interesting suggestion about interpretation on modern instruments, it gets hopelessly muddled when the score fails to distinguish between what content is the editors' vs. the composer's, as they so often do. Something like this of Bach's C major prelude from The Well-Tempered Clavier, book 1, shows basically all the different kinds of unwanted editorializing I described: https://imslp.org/wiki/File:PMLP05948-WTC_Mugellini_No._1-12...
A modern Urtext edition would also include detailed information about which manuscript and early edition sources it was prepared from, and any unresolved or variant readings between these sources, with performance suggestions (apart sometimes from fingerings) relegated to supplementary notes that are clearly written by the editors and not the composer.
I don't presume to know what they meant, but as an example of something I think fits the bill, I downloaded "Bill Bailey Won't You Please Come Home" and the lyrics are full of a certain type of phonetic transliteration from vernacular Afro-American English (as if it's a foreign language or something) the likes of which you would probably never see today (e.g. lots of "dat" and "dey" and "throw'd" and "de whole day" and so on).
You picked my interest.
- what makes an "edition" ("score"?) outdated?
- can you give examples for a weird editorial decision, maybe by additionally providing an alternative good editorial version?
- what happened that something deemed correct (?) over 50 years ago is nowadays something no one agrees with?