I do not see any way to trustlessly generate a blackballs database without running full nodes for malicious fork coins, which I do NOT want to do (and don't even have hardware resources to do). However, I need a working blackballs database to protect my rings against using outputs which are publicly known to be compromised across chains. Rock, meet hard place, with privacy-conscious users in between.
In this discussion on another question, a helpful user is distributing a blackballs list. As I observed it, it lists 16,427,618
txids 64-digit hex strings (Edit: see my comment to user36303's helpful answer). I appreciate the apparent helpfulness; however, hmmm... Attack: Distribute a malicious blackballs list containing 16,427,618 txids 64-digit hex strings which should not be blackballed. If I grok, this would be much worse than useless: It would significantly skew the probability toward randomly selecting outputs which should be blackballed.
Additionally, if the malicious blackballs database is large enough, I hypothesize that distributing different versions to different users may fingerprint them by differently skewing the distribution of output selection. I am less worried about this, due to the magnitude of numbers involved. I doubt it is a useful attack.
Note: I am not 100% sure of any of this. I have expertise in other coins, but I'm a n00b with XMR. Trying to do my homework, avoid common pitfalls.