Well, technically, even if the blood was dry, they would "swab" it. There are chemicals they can put on the swabs to help swab some dry things, but overall I think you are thinking along the right lines. Dry evidence, such as hair etc, would not be swabbed. However, say there was no visible blood in the SUV, they could add a chemical to a swab, swab the area, and get a preliminary positive result for blood. Am I making sense?
I was somewhat surprised by the taking of trace evidence from the hands at the crime scene. Usually the hands are simply bagged, then trace collected at the morgue in a sterile environment to eliminate any chance of contamination etc.