Some editors I've worked with have been very draconian about it, to be honest it shouldn't happen if three sets of eyes are proof reading a story... Still happens tho', obvs... I always enjoyed spotting them when I art checked a layout before sending it to press, so, so satisfying...
Nah, they'll try and get punny stuff in at any fucking opportunity but mistakes are a big no-no... You tend to get fired if it happens too often...