Banner placement is a typical use case where there are no explicit negatives: there are just clicks but no "not clicks". There's many such use cases.
The recommended pattern is to post a "negative" when the banner is shown ("impressed"). Ideally only when it is viewable by the customer, but if that's impossible even just a "negative" to all the top N decisions is an okay proxy.
In a slightly related use case, when an email contains multiple offers, should the email open, and the click-though on the individual offers both be positive outcomes for each offer - assuming the email delivery is a negative outcome for each offer?