Does the Infestor's slime trail ever serve a useful purpose?
Solution 1:
I'm afraid not, the infestor's awesomely gross slime trail is sadly, purely aesthetic.
Solution 2:
I think this trail of slime is rather disadvantage for the zerg player.
Because the slime trail of the Infestor lasts several seconds after the Infestor passes by, if your opponent sees it it can tell him/her both:
- You have Infestors.
- Gives an idea of where they're going.