Debuffs are also a lot of the times red. Then there are the other debuffs that aren't red but match the element the attack was. Then there is a Debuff called misery that Esuna can't get off but if you use /cheer or /rally on the effected player it'll be removed. It's mostly put on by gremlin type monsters. Just remember that you have to be near the person as emotes have a short effect distance. Another sometimes confusing debuff is doom. If it doesnt come off with Esuna and you're not running the sunken temple of quarn you'll have to heal the person with doom to max health. The charm that Siren in Pharos works in the same way where you have to get the person to full health to remove it.