Trust is a dangerous fucking stigma that affects dumb people, whereby people forget that all humans, including themselves, are bastards who have their own ambitions, agendas and personal searches for happiness which they will inevitably prioritise above other peoples needs and expectations. Investments of trust in other people are generally comparable in success to the maiden voyage of the Titanic, or the design of the Smart car, and can have varied lifespans (length of time before trust is withdrawn - usually prompted by the "trusted" person either sleeping with someone else, committing category A crimes such as watching neighbors or stealing from your stash, or something to do with money and where you keep it).
The theory that trust cannot be placed in anyone, and that all relationships are conditional, is beginning to become more widely accepted, as more and more screwups are being attributable to misplaced trust. All trust in humans with freewill is in fact misplaced - like for example Uncyclopedia's crazy decision to trust other random members of the public to post their own shocking material on their website (many thanks Uncyclopedia).
Trust has been misplaced throughout history many times - from Julius Caesar's trust in his friend Brutus, to Jesus actually choosing his friend-with-benefits Judas Iscariot as one of his twelve coven members, to the time on Family Guy when Stewie trusted Brian to pack his parachute.
Trust in inanimate objects is the only rationally acceptable form of trust (just ask any woman worth her salt who her best friend is, and how many batteries it uses), unless of course the inanimate object is Russian-built or bought on Ebay.
Trust, throughout the ages has been invested in many different types of people - the most common being the most popular character in literary fiction, god. This type of extreme misplacement of trust is a common symption of the virus of religion, and a primary constituent of faith in ghosts and vampires.