How would this look in practice?
In practice, when you view life as Epicurus suggests, you can find pleasure in all sorts of places and all sorts of things, so you're not going to normally find a "total absence of pleasure" situation. if you're absolutely unable to find pleasure, even using Epicurus' perspective, for some extreme reason, then you're probably approaching a "time to exit the stage" analysis because boy has the play really ceased to please you! But as Epicurus says that's an extreme and unusual situation, unless you want to count the state that all of us will eventually get to -- when we are at a limit of frailty of mind and body from old age. But most of the time long before that we meet our end from some other cause.
I'd say you could also simply recognize that any painful experience can justifiably be called an 'absence of pleasure' experience.