In the beginning, I would worry about getting caught. Now, with X-Rays and MRI's confirming the problems with my back, I really do not care if someone sees me entering or leaving a massage parlor. I would actually have a more difficult time explaining a visit at a distant location more than a local shop.
Guys, even if you are a picture of health, do yourself a favor and regularly discuss a tight, sore, stiff back with your SO. If you are ever seen, then someone can easily put 2+2 together and the ramifications will be much less severe.