I'm not even sure if "implied tailhole" should exist. It's just "character with tail is wearing a bottom and a tailhole can't be visually confirmed". Maybe the garment's waist just makes a dip to accommodate the tail? Should all these pictures be also tagged "implied waistband dip"?
Sorry, I'm a bit too tired to be answering serious questions.
/eta: oh lordy it's worde than I thought... so many of these actually *show* a tailhole, it's just not drawn in detail