I think who the plus one is - is irrelevant. It (and the cheap airfares for the family) just adds to the depth of the trough into which a snout is placed. All sweeteners and nothing more.
Anyway time to sign off
If one is of the camp nothing affects decision making and a few drinks in CL affecting judgement is a furphy then issues such as whether wives/partners/sons etc becomes relevant.
Others see it differently. My experience is based upon the specialist colleges own code of practice which actually define hospitality, entertainment and gifts and - not negotiable
Both sides of the discussion is valid