Say you have a field hidden with a div on a low profile, minimum traffic site (100 visitors a week). It's incredibly unlikely and pretty dumb for a bot to be m

Say you have a field hidden with a div on a low profile, minimum traffic site (100 visitors a week). It's incredibly unlikely and pretty dumb for a bot to be made specifically for that site -- in this case, how could a bot determine whether that field should contain a value or not?