Mistress has multiple definitions and is more a social construct than something you can see in a picture so I'm not sure how they come to a conclusion on that one. There do seem to be lots of BSDM style photos in that set which makes sense as that is the only discreet physical definition of a "mistress"
"foolish woman" Usually people say "idiot guy" but that comes up with Television which is often referred to as "Idiot box"
"Honest Woman" is defined on their site and seems to search accordingly. Also it is a common saying which probably matches the expected results of most searchers. Synset: honest woman Definition: a wife who has married a man with whom she has been living for some time (especially if she is pregnant at the time); "he made an honest woman of her".
The classification seems to be based off common speech usages and seems to be adhering to them.