I got 29 and was surprised how many I got right. Although several of them were kind of guesses - e.g. my reaction to the picture was "They look fed-up" and then that wasn't an option, so I compared each option to the picture and picked one of the options that wasn't a complete mismatch. (I thought a lot of them looked fed-up.)

I couldn't tell you what it is in any image that makes it look like the emotion it's supposed to look like.

I also noticed the way all the sex-related ones were women, and I'm not normally the sort of person who notices or cares about that kind of thing, so it must have been quite an extreme bias.