Couple things. I change the number from the default (3) and that usually seems to give me an accurate list.
Second, I don't use the nuke button. Actually put in the work to confirm some of them are inactive.
Discussion
that's too much work for me. i followed 1500 people. the tool recognized hundreds of people for me to unfollow. thankfully a better tool has emerged.
boom. i spot checked a dozen people and then nuked 139 inactive npubs.
Yeah, relationships do take some work.