Finger licking bad

When did that disgusting habit of licking your finger before turning a page go out of fashion?

I sat on the train this morning (in First Class) and watched a 60+ year old city type reviewing documents from his briefcase. Before turning the page he popped his finger in his mouth. I can remember my father doing this and have an 84yr old uncle who does it too. I can remember the practice being ‘normal’ but today it really does seem unhygienic.

What’s changed? Are pages now less prone to stick together? Or have we simply realised that passing round paperwork drizzled with spit is not very nice?