Vine Men, Vine Ogres, and Ivy Kings have 0 precision. That's okay, since they don't have a head slot either- no eyes! But if they don't have eyes or other normal vision-type activities, they should count as "blind", shouldn't they?
As they stand, they seem quite inconsistent. They should either have a non-zero precision (if they use something like normal vision/eyes), or the "blind" attribute (if they don't). IMO, the latter option seems more sensible and appropriate.
I'd call this a bug, but it's not a code error, just a slightly mismade line of summons