I got so used to checking the background first that when I saw http://whichfaceisreal.com/realimages/47361.jpeg my mind immediately told me that this one is fake.

It only took me a while to notice that this is an actual human face in the background, just photographed from a peculiar angle and bearing a peculiar expression - not a neural network artifact.

Check the background :D

In addition to the background, if you can see earrings, that is usually a giveaway. The generated faces seems to always have different earrings in each ear. Also glasses disappear into the skin, and ears are often different on each side and/or distorted.

It seems the model often doesn't do exactly round pupils either.

I'm 10 for 10 when I use the background to work it out. There are always little imperfections and whirls that give it away.

At least in these images, the skin and clothes are also not great if you zoom in.

Also look at ears and earrings.

If they're wearing glasses do the glasses look they were beaten into shape with a mallet?

or melt into the face

Just got 5/5 correct pretty easily -- is this using an older model, maybe?

The correct image was also on the left side all 5 times, which feels a little suspicious (although obviously not super unlikely).

Guessed 10/10, but that was much harder than 5 years ago.