now some states like Texas, have a law saying that if the business puts up a specific sign described in the law, then a CHL holder is committing trespass by going in anyway. in Texas the sign is required to be in 1inch block letters and have specific wording, if the sign is not exactly as described it carries no force of law.
my rule is this, if I walk up to a business and there's no sign immediately at eye level visible at the door I go in anyway.
most malls have a little sign where guns are prohibited in a big list of rules in little print, I don't seek those out. big sign eye level or I didn't see any sign at all.