Ambling around the stadium before kick-off on Saturday, I sighted a woman sashaying into turnstile 46 whom I suspected of supporting the visitors.
As a journalist you develop an instinct for this sort of thing, and my suspicions were first aroused when I noticed that she was wearing a West Ham shirt and taking selfies.
I have no doubt that she was a perfectly harmless lady and was off to watch a relatively unimportant match in the right spirit.
But she should not have been admitted or, failing that, ejected.
Not nice, I know. But for starters she was contravening the terms and conditions under which her ticket was purchased.
Those terms and conditions exist for solid reasons.
First there is her own protection. The vast majority of Sunderland supporters behave impeccably and wouldn’t have cared, but sadly no one in the “wrong” part of any football ground is immune from a bop in the mouth.
This is something that idiots who illicitly take Manchester United or Liverpool supporting youngsters into the home section fail to understand.
She did seem nice. But there is no foolproof way to distinguish the niceys from the not-so-niceys (and West Ham have form here).
Therefore, admit no one who is demonstrably in the wrong area.
One perfectly civilised Hammer? Okay, what next? Two? Three? Fifty? How many Newcastle fans should be given the blind eye the next time they are in town?
Zero tolerance is the only option.
Indeed, SAFC officially has such an approach (under sections 1.2 and 18 of its ground regulations if you’re interested).
If they could only pass this on to the uninterested steward who was standing two yards from turnstile 46, then all the better.