To me, there's 3 types of conspiracy theories;
1) The paranoid; They just think anything that is mentioned "NWO" is instantly a conspiracy. Any brand new ideas which are genuine seem to always somehow refer to the illuminati or some reptile alien species. Yeah. Retarded if you ask me.
2) The reasonable; They don't just claim everything is a conspiracy, they are aware of something is going on that the government does not want the normal citizens to know, some are well informed and actually look into it before they decide, they look at it at and actually check where the sources come from.
3) The "Question more"; They are skeptical on how the government runs, or wants people to portray someone else (Such as our supposed "War of Terrorism"), they ask more questions and want to find out the answers based on what they see, rather than a politician making claims or just saying that some country is bad because terrorists come from there.
To me, I find there are too many paranoid individuals, however don't claim a conspiracy theory is instantly false and ridicule it, sometimes the government/companies aren't always honest, and sometimes there is compelling evidence against it.
But to put it simply, if you are ever interested in any theories, ensure you find out what the motivation is, and what do they gain in succeeding it, don't listen to some conspiracies, such as the Haiti earthquake was caused by the US government, seeing as there's absolutely nothing to gain from it, or someone saying that a politician said "NWO" instantly means a conspiracy happened.
I've watched interesting documentaries that talk about how businesses works and how the government turns a blind eye to things. So it's not always the government, it can be businesses too.
Conspiracies have happened throughout history, such as Hitler getting the Nazi's to burn the Reichstag and then blaming it on German communists - and it worked perfectly well to convince Germans to not vote for the communist party and eventually forcefully kick out and exile the communist politicians.
Poisoned foods are not really a conspiracy theory - It's just so they can grow crops cheaply and make more money, just the chemicals they used just turn out to be harmful for us, but are not willing to change it because they want to grow it cheaply (or the chemical manufacturers don't want to lose money) - Which I normally call it "Business as usual".
Such as the Iraq war, just business as usual, banker's make profits from the government in debt, the oil companies make a killing from it, the weapon's manufacturers make a nice share too - Business as usual, no conspiracy, sure Saddam Hussein had used chemical weapons on citizens, which is completely wrong to use for any reason, but what Saddam did was a perfect excuse to profit from going to war in Iraq.