a fantasy: I get intestinal distress from food/water while on vacation. I take antibiotics to clear the problem. At a later date, I have a fecal transplant [0]. It couldn't be mine, because that was the site of the problem. Instead, I order a culture that matches my previous microbiome distribution.
I think to do this, you'd need data points that don't yet exist: if your microbiome changes from antibiotic use, will you suffer health effects (beyond infection with a disease causing bacteria like C. difficle)?