OkCupid, a dating site, does occasional analyses of site data to see what trends they can observe. Their latest analysis, published in a post titled "Don't Be Ugly By Accident!," had to do with which pictures on the site get the best reactions, and they found that the photos that perform best have a shallow depth of field (which, of course, typically requires an SLR with a lens that has a wide aperture), use natural light instead of flash, and are taken at the golden hour.
I just thought it was interesting for these aspects, which are ones that I had gravitated to "naturally" before I knew much about photography, to make themselves known even in this context. In turn, I suppose it is a little nudge to consider when taking our own photographs, whether or not they are for a dating site.
Be sure to take a look at the whole article for some other whiz bang comparisons and findings, such as comparing how attractive photos are on the basis of their depth of field, as shown above.