I have done spray tanning at a salon twice for special occasions. The one I went to did the spray by hand (I was wearing old undergarments) rather than the kind where you stand in a booth and the spray is done by a machine. They have more control that way and can work on the uneven tan lines better.
I did not get a patch test and had no problems. I don't have particularly sensitive skin, though. I did do all the suggested preparations (exfoliating, mainly). I loved the results. It did not completely eliminate my biker tan, but it certainly made it less noticeable. My tan looked completely natural. Unfortunately, it only lasts about a week.
Grits
2010 Trek 5.2 Madone WSD, SI Diva Gel Flow
2002 Terry Classic, Terry Liberator