A WarCraft III commentator told the story of how he once saw a pro, during the opening, send his Demon Hunter to the healing fountain on a certain map, and he started doing the same with the same timing on that map. One day he met the pro in person and asked why he'd done it, and the pro said, To see if the opponent's Blademaster was there.
The Demon Hunter and Blademaster is each player's respective hero/champion and essentially a free powerful unit.
The DH player has the advantage during the early game, so is scouting around the map (the Fountain of Health being a likely location) to find an easy fight.
