I have been grocery shopping en femme often and without any trouble. I just dress like the GGs my age for the occasion. The store knows that my money is just as green the next person's.
An anecdote about grocery shopping en femme: I went grocery shopping en femme and forgot my purse in the shopping cart in the parking lot. I noticed a couple hours later at home. I went back the the grocery store, a WalMart, still en femme. It was a busy day. I stood in the customer service line with everybody else. I told the agent my tale of woe. She looked at the other agent and said, "She lost her purse. There is one in the back that matches her description of it." The other agent went to the back of the office and came back a minute later with my purse. She opened my femme wallet and found my (male photo) ID. She asked my name and I responded accurately. She gave me my purse and wished me well. No one in line seemed to notice. The WalMart? At the corner of Academy and Voyager in Colorado Springs.
