ward recognition

So a few GvG matches ago we ran into a team using ok, but not great, positioning of wards. They threw up both ward against foes and ward against melee at different times/places. The thing is, I never knew which was which until I was in the ward (was I slowed or not). I know that wards change color (red or blue) depending upon whose team's they are, but is there a way to tell the difference between the two? I'd like to be able to recognize them to run around ward against foes... http://www.theamazonbasin.com/gw/forums/index.php?showtopic=7581