To some extent it is a matter of risk analysis. Good stories generally do not suffer from being spoiled, and are every bit as good on the second go-around (Yes, I know that there are exceptions, but they are VERY rare.). Likewise, stories that draw their vaule from a terminal plot twist generally just are not very good (and again, there are RARE exceptions).
What this means is that most of the time, nearly all of the time, the spoilers just don't matter. So the spoiler-phobe goes through life in a bubble of inconvenience (both personal and public) in order to avoid the vanishingly small possibility that a truly good story might be damaged by foreknowledge. Is it any wonder I pity such creatures?
It occurs to me that the correct response to spoiler phobia is to invite the sufferer to play poker. No limit Hold'em, intangible assets accepted.