The way I read your question is "Do Louisiana 'no gun' signs have the force of law?"
The answer appears to be YES, they do (very short on research time, and limited site availability, so don't take this as the only word for it): http://www.handgunlaw.us/states/louisiana.pdf
Here is the relevant text:
The provisions of R.S. 40:1379.3 (N) shall not limit the right of a property owner, lessee, or other lawful custodian to prohibit or restrict access of those persons possessing a concealed handgun pursuant to a permit issued under this Section. No individual to whom a concealed handgun permit is issued may carry such concealed handgun into the private residence of another without first receiving the consent of that person.
It also appears that OC is legal in the state (private grounds, and some municipalities may disagree, but there is a state preemption),