Consider that there are about half a billion people on Facebook. It is extremely unlikely that an employee that you are about to mystery shop will happen to run across your profile and will remember and recognize you when you shop them. Of course, it is not impossible.
Some employees actively try to identify the mystery shopper. There are some ways they might be more likely to discover the people who could be mystery shopping them than by trolling Facebook, but I am not going to explain them here because I don’t want to encourage anyone to try to identify mystery shoppers.
Obviously, mystery shopping companies do not have a problem with you identifying yourself as a mystery shopper on social media. If they did, they would not encourage you to like them on Facebook, follow them on Twitter, etc. Many companies announce shop opportunities on Facebook and Twitter, so shoppers who engage with them have an advantage in getting more assignments. So if you want to participate in social media as a mystery shopper, go for it.
There is a downside, though. When you join a mystery shopping group, “like” a mystery shopping company or otherwise make it known on social media that you are a mystery shopper, you are going public with the fact that you are a shopper. Although it is unlikely that someone you are going to mystery shop will recognize you from that, you will be letting your Facebook friends know that you are a mystery shopper.
The more people who know you are a mystery shopper, the less “mystery” there is. For example, if your friends all know that you mystery shop they may want to know how to become mystery shoppers and give you more competition. Or worse, they may inadvertently “out” you if they run into you while you are doing a mystery shop. Imagine you encounter one of your friends while doing a shop. She turns to the employee and says, “You’d better be nice to her–she is a mystery shopper!” Your friend was making a joke, but she just invalidated your shop.
In general, the fewer people who know you are a mystery shopper, the better. However, I have been a very public mystery shopper for many years. I have trained more than 10,000 mystery shoppers. I wrote a book about mystery shopping. I have been featured in magazines and interviewed on television. And even with all that, I have never had an employee recognize me as a mystery shopper. (If they had, they would have gotten better scores!)
If you want to participate in social media as a mystery shopper, go ahead. If you prefer not to, that is fine, too.