Not only does Scout's jizz Mad Milk let your team heal from damaging coated bots, it also slows down the bots after spending just 200 bucks to buy that upgrade. That is a must should you come to a mission with those dreaded Super Scouts, sir!!!
When I play Scout I always upgrade myself against all kind of damage (bullet/explosive/crit/fire etc..). My loadout is FAN (cause of knockback), pistol (I haven't found the milk yet), and Fan o War for the big guys