This from the wonderful LongHairGal :
" Remember, the shunning routine doesn’t work without an audience to appreciate it."
What a great point ! I think too, if we get the chance to negate what they do, by giving them at least a cursory nod, or even a "Good morning" and even a smile ? as you would any person you once knew, it is great to do, preferably without engaging in conversation, they don't deserve that, but then they know their Shunning attempt has failed.