In my mind, there are two kinds of idling: passive idling, and active idling.
Passive idling is doing nothing and not gaining attention. Active idling is moving around and gaining attention, but not completing missions.
Passive idling is the best way to look like an AI, because AI are so fond of doing nothing. The most passive idling is just standing in a conversation: you aren’t finishing missions, and you aren’t giving the sniper any reason to care about you. This is unsuspicious, but a weak play, because you never show on the sniper’s radar and are therefore unlikely to be lowlit.
Passing idling is better for framing someone, given how much more attention you can dedicate, as spy, to watching the party and choosing your victim. But it still usually requires that you show a hard tell. From the sniper’s perspective, lowlighting for passive idling is good in a vacuum, but you have to take care to not lowlight for timer flirts. And, of course, time spent watching people doing nothing takes attention away from people at mission sites.
Active idling is different, and more interesting. Examples of active idling include things like taking a book out, walking around with it for a bit, and then returning it to the correct shelf. Or visiting the same statue twice. Or picking up a fingerprintless briefcase. Like passive idling, you may not be getting anything done, but you’ll be doing it in a way the sniper is more likely to see, and therefore more likely to lowlight for.
Active idling can backfire, because snipers miss things. Walking around with a book and putting it back only reduces your suspicion if the sniper is confident they know where it came from; if they’re not, you’ve made yourself more suspicious for possibly completing microfilm. When you go to the same statue twice, you obviously may be credited with inspects, and now possibly a fingerprint, if the sniper is not similarly confident there is none there. And sometimes the only reason they would be watching you closely enough to be confident about all these things is if you’re already highlit, which is hard to shake.
Active idling, then, is risky for the spy, but that’s precisely what tempts a sniper to reward it. Personally, I like to reward active idling by bumping highlights down to neutral. If a spy is willing to spend 90 seconds walking a book around, even if I decide to lowlight them, they will struggle to finish, risking either a time out or a late desperation rush.
I’m far away, skill-wise, from being able to lowlight someone who looks like they’re “flirting” with too many different people, but that feels like the strongest form of AI-like active idling, given how much spies abhor entering conversations without a Seduction Target or Double Agent these days, generally preferring a nice window or painting from which to plan their next move, and avoid the conversation etiquette traps.
Which style works best should shift from opponent to opponent, and even game to game. Sometimes minute-to-minute, if you become convinced you active idling has paid off with a lowlight, and you can beginning completing missions in (relative) safety.