A phrase I commonly hear (and use myself) when a company (or individual, in some cases) does something that seems foolish or not planned is to ask
What kind of Mickey Mouse operation are you running here?
A search on Google leads me to Urban Dictionary, who confirms how I have been using the expression to mean
Substandard, poorly executed or organized. Amateurish.
However, The Walt Disney Company is one of the largest entertainment corporations on the planet today. This Google Ngram shows that the expression did not become popular until about 1970s, well after Mickey was created. While I know the company did not achieve their current, prestigious status overnight, and I am not looking for history of company…
Why did the expression become popular and have a negative meaning associated with it?
The phrase isn’t referring to The Walt Disney Company itself, but the misadventures and simplistic mindset of the original Mickey Mouse character for which the company is famous.
Courtesy of NVZ:
noun 1. nonsense; something trivial. (From the world-famous mouse character by the same name, owned by The Walt Disney Company.)
"This is just a lot of mickey mouse."
informal 2. not important or not good compared with other things of the same type (always before noun)
"We’re talking about a respected organization here – not some Mickey-Mouse outfit."
The phrase is a reference to early Mickey Mouse cartoons, in which Mickey is often a laborer or professional of some sort who is swept up into a comedy of unprofessional errors and wacky, nonsensical pandemonium. An example of this is the character’s first appearance in the short "Plane Crazy (1928)."
The overly simplistic mindset exhibited in the inept, muddling, amateurish way Mickey and his organization attempt to achieve flight in this example is the type of thing the phrase connotes, and is hence the reason it carries a derogatory meaning when applied to the way a company or organization is run.
The popularity of the phrase took off as the character’s popularity did throughout the second half of the 20th Century, buoyed by The Walt Disney Company’s growing television presence, most notably its long-running flagship primetime series, The Wonderful World of Disney (1954-1992). Also (perhaps coinsidentally), the generation that grew up watching The Mickey Mouse Club (1955-1958) were entering the workforce in droves during the 1960s and ’70s as young professionals when the phrase seems to have risen sharply in popularity.
Appendum: further relevant info Courtesy of nedibes:
The decline in the quality and financial success of The Walt Disney Company’s merchandise and films during the late 1960s and throughout the 1970s may have further contributed to the popularity of the phrase "Mickey Mouse Operation." Following the death of Walt Disney in 1966, the company seemed to lack a clear vision and direction, similar to the way Mickey himself seems to approach things in his cartoons. This period is often referred to as the "Disney Dark Age."