> Heard this from an Indian friend, and not sure how much of this true - Indian cities used to have problem of folks chewing tobacco and spitting everywhere, so in some places they would have an icon of a Hindu god, and it worked (maybe not with non-hindu).

Probably worked with non-hindu as well; after all, people don't usually spit on or in front of religious idols even if those idols are from a different religion.

You don't need to be religious to not spit in front of an idol... I mean if someone put their bag there you would also not spit there. The experiment needs to be repeated with more items!