In the beginning of my MS career, I would leave a bank, for instance, muttering, "Female, blond, shoulder length, glasses, white blouse, blue scarf and jacket, 5'6"-5'8". Over and over until I reached a safe place to jot it all down. And, I had the good luck to be able to walk back into the bank, if necessary, to refresh my memory or to make a missed observation. Now, I drive out of a parking garage, with no chance to return to check something out, but still muttering (a much longer list of demographics including age range, ethnicity, tats, body type, for those shops) until I can find a safe place to pull out of center city traffic to record or jot down those details. I have aged a lot in those 11 years, but my memory has actually gotten better with all of the practice. Because I am much less nervous, I can much more easily "replay" an interaction in my mind. Hours later, I can see the target and replay where the cash was placed and whether or not there was an electronic display of the price/fee. These can all be new skills you can practice.
I really think it has to do with "being in shop mode/concentrating." In "real" life, one is not always in that mode. For instance, I still go to my kitchen, then stop, and try to figure out what I came looking for!
Based in MD, near DC
Shopping from the Carolinas to New York
Have video cam; will travel
Poor customer service? Don't get mad; get video.