Rule #19: Always open a guest's bottle of wine in front of him/her.
Whether a customer has ordered off the wine list or arrived with their own selection, you must open the bottle at the table. If the wine opener gets stuck or begins to destroy the cork, you may be tempted to excuse yourself with the bottle to avoid further embarrassment, and open it in the kitchen, the break room, or God forbid, the bathroom. However, this is considered ill-mannered and impolite.
Opening the bottle at the table assures the customer that their wine hasn't been compromised. If the cork is rotted or the wine smells off, oxidization, maderization, or leakage may have occurred. You'll be free from blame.
If you are having difficulty opening the wine, enlist the help of a colleague or hand the bottle over to the customer to cork. You'd be surprised how many people are just hoping you'll ask.