Well for me, it's not 'whether' but 'how'.

I don't mind anyone chewing gum, providing they do it in a way that means that I don't actually SEE the gum that they're chewing.

The vigorous, open-mouthed, watch it roll around my mouth, chewing is disgusting to see; but someone gently masticating with a closed mouth is no big deal.

Alex Ferguson is a good example of how not to do it. (Chewing that is, not managing!)

K/van