Conspiracy theories have many things in common. The greatest commonality, however, is the conspiracy!!! OMGDZ11!1!!!!eleventy!one!
A "conspiracy" is defined by Flebster's Modern Dicktionary of Some Random Language as "Some con artists engaged in piracy".
 OMG numbers!
Look! When I calculate the letters in "sacrifice", I can find a way to make it meaningful! Isn't that amazing?
 Stupid evil people
Evil societies, instead of using their vast resources and influence to just fucking buy the planet, sit in the background and waste their money manipulating our sacrifices. Of course! I knew it all along! DAYLIGHT SAVINGS IS A MASONIC CONSPIRACY TO ROB US OF OUR SUN!!!
 The Department of Making Things Exponentially More Difficult
All conspiracies have an entire division devoted to fitting their schedule to match obscure astronomical events. This makes for one hell of a handicap.
I imagine, every now and then, they have a conversation that goes like this:
"Jenkins, are we ready to implement our ultra-secret super-awesome plan?"
"Yes sir, but we missed the passing of the constellation Orion at a 33° angle over the earth... I'm afraid we'll have to wait another ten years for it to come around again"
"Damn you, Orion! Always foiling our plans!"
"Ain't that funny? By analyzing photographs blown up to the point where we can see the pixels, I can read whatever I want into the pixels."
"For example, those fuzzy black-and-white blobs right there—here, I'll zoom in on them for you—" *zooms in to where you can't make anything out anymore* "OMG buildings! OMG a wall! OMG a face!"
I made a special hybrid in my greenhouse, but the Monsanto black helicopter came in the middle of the night and stole it!!! It would have made 95% pure alcohol to run our cars, from the air and sun, with my carefully bred orchid! man, I got so ripped off, and so did you. Cil Monsanto!
 No Evidence
I mean, I had all the evidence right in my garage, man, but the oil companies sent a goon squad to clean it up, and now I'll never be able to duplicate my invention that lets you plug appliances right into the ground.
 Don't Fall For It!
Don't believe the Government's and Big Oil's obvious LIE that they only came into my garage because I illegally bypassed my electrical meter! That's just what THEY want you to think! And, in fact, they MAKE people think it with their evil MIND-CONTROL helmets! (Which I invented, but they stole them from me too!) Put on your tinfoil hats!
 Dept of the Obvious
Sometimes rich people, or foreign countries, or companies, get together and make plans that they don't want made public! It's a conspiracy, I tells ya! There have never ever been a conspiracy, you sick morons, it's impossible and never happens.