Can you fail an ETG test from foods cooked with alcohol? Please help.

Mostly it is going to depend on what type of foods we are talking about. Many cook use it to add flavor to foods but the alcohol is burned off in the process. Some deserts have alcohol in them and those are the ones you would have to avoid eating. If there is any question about what your eating then ask the cook. DO NOT rely on your waiter.

Can you fail an ETG test from foods cooked with alcohol? Please help.

This is a common misconception. While there is alcohol cooked off when used in food prep, it isn't all gone. A lot of sauces or what not that use a wine as a base will still have alcohol in them. It is at such a low concentration that you wouldn't notice nor get drunk off them, but it could tip you on a EtG/EtS test. The best option is to just avoid any foods that could have alcohol in them.

It may be a very small factor, but one you cannot completely ignore.