Earlier this month, Google Image Search had a bug with their reverse image search feature. The feature you upload an image and Google tells you more about it.

In short, it seemed to not be finding relevant images based on the image you uploaded.

There is a big thread about it in the Google Web Search Help forums. The first report came on July 30th where a searcher said:

Truth is, many were not getting relevant results with the feature. Then suddenly, after a few weeks of issues, last night, Google seems to have fixed it. Marco in the thread wrote “it seems that Google Search by Image is recovering,” and he posted on his German blog more details about the bug and fix.

I mean, it isn’t always perfect, at one point it thought that I was a porn star, no joke:

Google has still not confirmed or denied anything. So we do not know if this was a bug, intentional change or something related to spam. But it does seem to be resolved.

Forum discussion at Google Web Search Help.