There's no filter that will accurately cull the mail scanner clicks and visits based on individual activities.
And this is by design: as mentioned elsewhere, the intent of the mail scanner is to behave exactly like a real human interaction. If there were a technique to distinguish machine hits from human hits based on a single click/pageview, then the mail scanner would be entirely worthless, because the malicious actor would simply use that exact technique to avoid detection, then deliver the malicious payload to humans.
The short answer: stop scoring on clicks.
The longer answer: if you extract all your activities (using the Bulk Extract API) to a database, you can make more granular decisions about the frequency of clicks in a rolling window and then reimport into Marketo with field updates. It's still not 100% correct, and won't be in real-time.
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