I had the same problem. You need to look around in the specific area AT NIGHT for more hookers to spawn. Driving around during the day, there are practically none. Then, remember, you're looking for one of the fatter hookers, not the skinny ones. As mentioned before, just grab one of them as a human shield and Smoov should show his head.
aha ok thank you i try to get him :) i was quite lucky to get the luchadore cause i had a survival missions with luchadores and dragged them down to the place i had to kill him hope i get this one too, anyway, can i complete all my challenges if u completed the game?
PS3 PSN is gzes89 my FC = 2835 9337 9701 name is gianni