Marked cars sit in the parking lot exit lanes so it looks like they are ordinary cars waiting to get out (until you get close enough to see who they really are). I’ve seen them use different low-traffic parking lots — the one in front of the now-closed Outback Steakhouse, and also the one in front of the black office building at 9990 Fairfax Blvd. There are a lot of trees along the side of the road coming up to those two traps, so you probably won’t notice them if you’re not looking for them.