Hmm, if it's lighthearted deception that isn't harming another person, or perhaps deception to prevent others from being harmed, I have less of a problem with it.
From a concept like the tales we tell children of around the holidays like Santa Claus or the Easter Bunny, to deceiving someone holding an innocent at gunpoint, those are the sort of areas that I see it as acceptable by my personal standards. The former creates a fun atmosphere for the occasion, and the latter can help subdue someone in an unstable state while protecting another, or a multitude of others from harm, or even death.
Deceit to manipulate others into fulfilling a person's own selfish desires though, that sickens me. In love, in law, in business, it happens in nearly every field and it drives me insane simply to be around. Unless there's a damn good reason, it's something I find completely and totally unacceptable by any standpoint.