I can't tell if there is an icon in the buff bar at the top (it's too full), but if you hit F1 and then press 'z' you'll see whether you have it or not. It's the standard exclamation icon with the text "You smell delicious ...to a mimic."
It'd be nice if the mimic bait stood out some other way. Didn't the buffs from Cove and Mabar potions show up just below the buff bar?
EDIT: ninja'd by a dev