voting behavior that's indifferent to the voter's subjective appraisal or reasonable expectation of their subjective appraisal of the content
eg Vote selling: if I vote based on who pays me the highest rather than what that content is. Circle jerking/post farming are all similarly content indifferent.
How would you operationalize that definition? That is, which formal criteria would be useful at the detection of such behavior?
You can't detect it precisely unless you're the voter yourself, in which case you know pretty well if it's the content influencing your decision or not (eg if they're paying you to vote on their post, or if you're voting on their post because they're voting on yours in some stake weighted arrangement etc)
Externally, for now there are generally many hints as to whether the vote is bought or part of a circle jerk or some other dishonest scheme. Eg. If there are on chain links to vote buying.
Ultimately, if these things become less telegraphed, people will just have to get into the habit of downvoting whatever they believe is over rewarded more generally.