An important point, Section 46.035 of the Texas Penal Code says:
"(b) A license holder commits an offense if the license holder intentionally, knowingly, or recklessly carries a handgun under the authority of Subchapter H, Chapter 411, Government Code, regardless of whether the handgun is concealed, on or about the license holder's person:
(1) on the premises of a business that has a permit or license issued under Chapter 25, 28, 32, 69, or 74, Alcoholic Beverage Code, if the business derives 51 percent or more of its income from the sale or service of alcoholic beverages for on-premises consumption, as determined by the Texas Alcoholic Beverage Commission under Section 104.06, Alcoholic Beverage Code;"
So if a reasonable person would have realized that the place they were carrying in derived 51% or more of its income from the sale or service of alcoholic beverages, you can still be convicted of a crime, even if the 51% sign was not posted.
So if you are in the local watering hole and the only thing on the menu is beer and tequila and a bowl of peanuts on the bar, don't assume you are legal just because you don't see a 51% sign.