I, for one, never ask for a businesses position or permission concerning OC. Either there will be no problem or I'll be asked to leave. Either way is OK with me... I'll either be back to spend my money in an OC friendly place... or I'll never be back to a business that either bans guns... or discriminates against guns in plain sight while not extending the same treatment to concealed guns. And I also believe in spreading the word about those businesses that engage in discriminatory behavior.
If we limit our OC'ing to just those places that have been found to be OC friendly... there will never be any new OC friendly places and the word about OC won't spread because no one went there to find out... not to mention someone had to go there once before to find out first.
On the other hand... as is sometimes the case... if the occasion is one where any hassle from OC would be problematical... do as many others do in that circumstance... don't OC.
Just my 2 cents....