Why would anyone taking over the world, let alone a group of "aliens", announce themselves, admitting they are involved in a plan to enslave mankind and risk jeopardising the entire operation as well as cause a massive uprising?If some alien race has taken over the world then surely they would be smart enough to know that it would be more beneficial to them to either completely enslave us, or exterminate us all together. If they thought it better to stay hidden, then they are a dumbass race because to stay hidden would mean you have pretty much no control over things. What are they controlling in the first place? Our lives? How can they control our lives without us knowing any hint of their existance? What do you think our lives could be like if this supposed "evil race" wasn't "here"(I use quotations to emphasize skeptisism, not a theory)? They would have to have amazing technology to get here in the first place, but I highly doubt they would be the stereotypical aliens with mind-controlling powers and all that jazz.
Also, the idea of taking over a planet like Earth, from an alien race at least, doesn't seem very logical in the first place. Earth is a tiny mother fucker and there's almost nothing of value [to us] around it (not to mention the lack of planets with any form of dense atmosphere at all around it) so what race could possibly benefit from taking over this little speck we live on? We have our crap on the planet, but there's nothing anywhere near us. Hell, even our sun sucks donkey balls. The only purpose I see in that is for research on humans (aliens to them) and if that's the case then it's really not domination in the first place, but just an experiment of sorts.