Indicators
Indicators can be interesting when they are observed locally or provided by a high-confidence threat information source. IoCs, to be interesting, generally need to be emerging. IoAs have a bit more staying power.
Interesting indicators are also indicators that are contextual and enriched. Simply an atomic indicator by itself is almost next to useless. When it became malicious, in what way was it malicious, how has it been observed being used, and so on, is all contextually relevant information that makes an indicator "interesting."
Commonly, organizations can lose interest in an indicator when they have a countermeasure in place. While that certainly helps mitigate the threat, the indicator is still interesting in that someone attempted to use a known-bad indicator to compromise your environment.
An indicator can quickly become less interesting once it begins to become stale or decay (more on that in the next section). Additionally, indicators that are lacking...