One complaint and a few posts edited. Behave gentlemen.
On a side note, cops are expected to know the law and abide by it. Although states can have similar laws, there are always going to be some differences in laws from state to state. Expecting otherwise is foolish and can become expensive.
In at least some states, trespassing laws are usually different from trespassing while hunting laws. In most states, hunters are expected to know the boundaries of private property when hunting and are required to have permission to hunt said private property. In Ca, a hunter is required to have written permission on their person so DFG can check in the field and not have to try to find a property owner or agent to determine if a hunter is trespassing while hunting. A person not hunting, however, would be investigated as to whether they have some legitimate reason for being on the property (trying to contact owner about damaged fence, etc.) and whether the property was posted or not could also make a difference.
Consider using ignorance about property boundaries as an excuse if you trespass while hunting onto a game preserve, Indian reservation (federal laws kick in), military base or even just inside city limits where hunting is prohibited. I doubt it would fly very well.
As far as the idea of suing a DNR because a store sells deer (or other animal) bait, I'm not sure how that would work or that it would prevail.
If the bait is legal to sell outright (i.e. it's just animal feed), then the store is legal to sell and anybody is legal to buy. If a person legally bought bait and then decided to use it for an illegal purpose, I don't see how any attorney would be able to prevail in an entrapment case against a DNR unless it's a DNR owned store and they somehow encouraged (sought to entrap by) illegal activity.
Now if the bait is illegal to sell, then the store and the buyer are both committing a crime but nobody posted anything to that effect.