I'm trying to understand the intent of this feature. Is it an invitation to help HN to decide who is posting good content and who is not, and we are supposed to vouch frequently. Or, it is only for some corner cases and we should not touch it too often.
So its basically community moderation and you should "Only rescue civil, substantive contributions to the site". In a sense, I think its something you only do as a special-type thing, but one vouch on a post won't rescue it (there need to be multiple vouches if I understand it correctly)...so vouch if you want to, but make sure you're doing it for the right reasons.
FWIW, I've always treated the "vouch" feature as something to be used fairly infrequently, for somewhat exceptional cases. I don't know if that's actually the intent or not, but it "feels" like the kind of thing one shouldn't be doing all the time. shrug
