The only issue I've ever had on that front was with my wife. On a recent trip she saw a sign at the hotel we were staying in which said "Guns are not permitted on these premises". Thinking that she was being helpful, she asked the check-in clerk whether they had a safe so her husband (me) wouldn't have to leave his gun in the car
. She may have received oral notice in response. Thankfully I was not with her at the time, so I did not receive any form of oral notice...I had a chat with her about trusting me to know which signs are, and are not, enforceable.