I'm not one to get bothered by it, but my hubby would not think it was funny, especially if it was one of the photos he was planning on blowing up and framing. He tries to get photos with as little strangers as possible in it - he will scope out areas for hours to find the perfect spot....his logic...why does he want photos of people he doesn't know. However, understandably, we are at WDW and are expected to get other people in it, but if we waited for the PERFECT opportunity to take a photo with hardly any others in it and the castle in the background and someone came and photobombed our photos, I think my husband would be really mad.
However, I am all for silliness too. If I found a couple of photos that had a person in the background (see post above) that made me laugh, I wouldn't mind either.