Check out this addon:

http://wow.curse.com/downloads/wow-addons/details/dispelborder.aspx

It puts a VERY NOTICEABLE sparkle effect on any debuffs you can dispel from an enemy target.  This has been extremely helpful to me in both RBGs and arenas, as it allows me to see at a glance if I have cleaned the kill target of buffs, while still keeping an eye on positioning and health meters.

Seems to work with both stock unitframes and Xperl.

Happy dispelling!