Its on a case by case basis for me. I like signs of use in my posters, but a stamp over a face or in an important part of an image is a non-starter.
I found it interesting that some said the postage stamps are OK, but the rubber stamps aren't. To me the postage stamps are more intrusive.
I tend to agree that snipes are generally poorly done, a distraction, and something I would have removed during restoration.
And No, I have never had a Canadian censor stamp bleed onto anything else.