Ask HN: Is it OK to vouch for many posts?

I turned the "showdead" feature ON and now I see many posts with the [dead] marker. Some of them are interesting and I'm tempted to click "vouch" on some of them. If I do this too often, won't it hurt the reputation of my account somehow? I mean, am I allowed/supposed to do this frequently or this "vouching" feature is for emergency only?