After I wrote my previous post, I remembered the furore about a winner of the National Portrait Gallery's annual prize for a photographic portrait. These days, it is called the Taylor Wessing Prize, but back then it was sponsored by Schweppes. I cannot find a particularly large version of the image, so instead I have linked to an article in the Daily Telegraph which has an explanation of why this image won. Quite sensibly, the photographer (Shara Henderson) does not have it on her website, even though she won £15,000 for it. And that was back in the day when £15,000 was £15,000.
http://www.telegraph.co.uk/culture/art/3647686/Viewfinder-Girl-with-Baby-by-Shara-Henderson-2004.htmlThere was a lot of derision about this picture at the time and it is pertinent to this discussion when you look at the dainpipe in the background, although it is not quite growing out of her head.
This is just one of the reasons why it is impossible to answer your questions. Different people have different standards and to some a distracting background will be acceptable, to others it will not. In club photography, the latter will usually apply and, as you have noted, most judges would mark down such an image for the "fault". For others, it breaks the "rules" of composition, for which it is to be commended. You pays your money, all £15,000 of it, and takes your choice.