Here's a large Google Image Search bug. These searches contain two keywords: 1) an instance, and 2) the exclusion of a broad including category.
Search for roses excluding flowers:
16 out of 20 of the images displayed are roses.
Search for ants excluding insects:
20 out of 20 of the images displayed are ants.
Search for circles excluding shapes:
18 out of 20 of the images displayed are circles.
The bug is the following: Google Image search does not understand simple semantic relationships.
The image search algorithm does not know a rose is a flower, an ant is an insect, and a circle is a shape.