Currently, there are over 80 "reality" TV shows on the air, and several hundred more that have come and gone, all of which purport to show the "state of things as they exist" (the definition of "reality"). Viewers are captivated by a glimpse into the everyday real life of a famous actor, or by following a relationship as it blossoms (or withers, as the case may be), or imagining themselves being chosen by America as the next best thing. But the truth behind reality shows is that there's very little "reality" involved, if any at all. From mixing and matching video and audio, to creating storylines, to making decisions for contestants, to outright manipulating vote totals, it is no secret that producers do whatever is necessary to get people to watch their shows so that advertisers will pay for commercial time.
While it doesn't seem right that producers can outright lie to viewers, from a legal standpoint, there is nothing to prohibit it. There is no law or legal theory (i.e., fraud, misrepresentation, false advertisement, etc.) that imposes an obligation on producers to stand by the classification or definition of a show as a "reality show" or to be truthful when broadcasting a show to the viewing public.
What about the rights of the contestants or participants? Don't the producers have a legal obligation to them to portray the truth, or at least attempt to present a factually accurate portrayal of the events? This is where the lengthy contract usually signed by the contestants comes into play which gives the producers indisputable discretion to do whatever they want.
In general, contracts between producers and contestants are very clear: The producer can do whatever they want, with little or no regard to the contestant whatsoever. In fact, the contract will usually expressly state that the participant may be subject to invasions of privacy, defamation, and embarrassing situations which may expose the participant to public ridicule, humiliation or condemnation and that the contestant cannot hold the producers liable. The contracts even go so far as to specifically state that the producers may portray the participant in a "false light".
And yes, even the shows in which "America votes" each week may be manipulated. The contracts signed by the contestants of these "America votes" competitions usually acknowledge the broad power of producers over the votes and voting procedures, including the producer's unfettered right to "limit the number of votes accepted."