What are the signs of someone who is doing chew tobacco?

ththey might have a ball loking item on their cheek and their breath might have the smell of tobacco

there teeth may yellow progressive lack of money if young and storing of bottles and cans

Also:

Fingers and nails may become stained yellow from "pinching" the tobacco.

Look for empty cans in trash/drawers/car/etc.

Look for circular shaped wear marks on pockets of jeans/shorts.

Excessive spitting may be a habit formed by using chewing tobacco.

If they are really addicted they may become irritable after long periods without use.