I have been disappointed lately with the search results of search by image on Google, Bing and Tineye. I suspect censorship. Someone on here mentioned Yandex.com and I have done some experimentation with it.

I used some images out of my personal library and found that where Yandex got a hit, it could usually find other images of the same model. I used images of nudes for all my searches. I suspect Yandex has facial recognition in it.

If you have an image and want to find more like it, give Yandex.com a try.

There is also https://www.reddit.com/r/pornID/ where you can post pictures for others to identify, however it would be really easy for an image there to get buried since the volume of posts is very high.

If there are any other good image search engines, I would be pleased to find out about them.