The bottom line is that it all depends on your current skin tone. If your skin is already significantly darker than my darkest solution it's not going to do much of anything. For skin tones that are on the lighter side of dark (if that makes any sense at all), an airbrush tan still isn't going to make you much darker. It will, however, help even out skin tones.
If the shade of your skin is similar to the women below, an airbrush tan will work fine for you. It will make your skin only slightly darker, even out skin tones, and help hide imperfections.
If your skin is close to the shade of these women, an airbrush tan will not make you noticeably darker but will still give you a nice glow and blend imperfections.
If you are as dark or darker than the women below, an airbrush tan is not recommended for you. It is very unlikely that the tan will show up, or cover imperfections.