Tennessee's new law starting on Friday may help eliminate "gun free zones" in the state. It would allow a permit holder to file suit if they are injured by a criminal and were disarmed due to a "no guns" sign with the following conditions:
http://dennismichaellynch.com/see-how-tennessee-is-discouraging-gun-free-zones/
Link to the bill: http://www.capitol.tn.gov/Bills/109/Bill/SB1736.pdf
I guess this takes care of the situation where it's not illegal to ignore the sign itself, but the shop owner has you kicked out for arrested for "trespassing" if you do carry.
They were authorized to carry a gun at the time of the incident
They were prohibited from carrying a firearm because of a gun-free sign
The property owner was not required tobepost a gun free zone by state or federal law, but instead posted by choice
http://dennismichaellynch.com/see-how-tennessee-is-discouraging-gun-free-zones/
Link to the bill: http://www.capitol.tn.gov/Bills/109/Bill/SB1736.pdf
I guess this takes care of the situation where it's not illegal to ignore the sign itself, but the shop owner has you kicked out for arrested for "trespassing" if you do carry.