Do you think a twist is spoiled if someone tells you there is going to be a twist? I don't think so because you're not told what the twist is, you're just aware that there is going to be a twist and you are anticipating it.
That brings me to think about the genres on this site: the Shock Ending category is considered depreciated and it's been removed from well known stories like Candle Cove. Why? Is it because of that belief that if you're told there's a spoiler, that's as bad as getting spoiled? On the other hand, if I want to read a story with a twist ending, then I don't mind browsing that genre.
I don't think you're spoiled if all you are told is there's going to be a twist; it's just a matter of finding out what the twist will be. I still feel satisfied when the story reveals it at the right time.