Hell yes, not as much for mountain bike races, but definitely in bigger road races where more than just the local racers who I already know will show up. I even go so far as to Google them to find pictures so I’ll be able to pick them of the crowd. When a break happens it’s good to know if the people in it have a chance of making it stick. I also like to know who the contenders are and which wheels to mark.
A few weeks ago when I pointed out a pothole the guy on my wheel, who I didn’t know from Adam, addressed me by name when he thanked me for pointing out the hole. I guess the stalking goes both ways. There’s nothing wrong with scouting out the competition.