One of the big conspiracy theories going around the internet (especially Youtube) is that the music industry is controlled by the Illuminati (mind you of course there is no proof that the Illuminati even exists in the first place).
One of the key pieces of "evidence" that many conspiracy theorists claims is "proof" that the Illuminati is in control of the music industry is that many musical artists tend to use hand gestures and symbols (along also with certain lyrics) that many conspiracy theorists believe contain pro-Illuminati messages, or is being used as some type of brain washing techniques.
Now besides the fact that a very secretive group (such as the allegedly existing Illuminati) probably wouldn't be so bluntly giving away their existence by having a bunch of musical artists basically giving their audience a bunch of little subtle hints of that group's existence, it would kind of defeats the purpose of a secretive group being a secret to the public at large if they gave away their existence so openly.
Musical artists can be a weird kind of bunch. They constantly "reinvent" themselves or evolve in there tastes for two main purpose: To express themselves artistically, and to stay relevant so they can make money from teenagers and young adults, because that is where a large part of where music sales come from. There is even speculation that some musical artist that are accused of working for the Illuminati are actually intentionally using what is considered Illuminati symbols in their acts and lyrics in their music in order to generate controversy, and thus publicity.
There are also other claims by people who claim to have worked in (or currently are working in) the music industry, and that they have actually "witnessed" either what they consider to be Illuminati or other occult type ceremonies occur in private with some of these musical artists. These claims tend to be few and far between, and could be simply the result of misunderstanding the actions of a musical artist (as I said before, they can sometimes be pretty weird and do weird things) or everything they are saying could just be entirely made up (including their involvement with the music industry).
Even if this was true, the music industry would not be a very good industry for a secretive group to secretly spread messages of their existence through symbols (rather then outright saying that they exist).
Besides the shear fact that many musical artists are very independent minded and would most likely never go along with being apart of the Illuminate (some of which are conspiracy theorist minded people who would have no problems exposing this) there are thousands of people who work in the music industry, and there should be a lot more evidence being brought forth, and a lot more people coming forth and claiming that the entire music industry is being controlled by some secretive shadow group.
Also, another reason why the music industry really wouldn't be a good place to do something like this in the first place is because musical artists come and go all the time, with maybe only a few lasting a decade or more (as comedian Chris Rock once put when he was talking about musical artists "here today, gone today" because that's practically how long some of these artists careers last). So with this being said, would you really want to use the music industry to secretively spread a message (without even hinting what that message was)?
From what I can tell this is simply a new spin on old accusations that have been plaguing the music industry for decades about how the music industry is being controlled by secretive and malicious forces, such as Satanists in the 1980's and 1990's, and communists even before then.