I'm not entirely sure, but isn't a strider covered in someone else's blood also sexy? What if their blood isn't sexy in itself, but it's some sort of trait that comes with their skin? Maybe its their hair? I bet its the glasses.

a strider covered in anyone’s blood is pretty much the sexiest thing ever. being his own is an added bonus.

glasses definitely help. i hear it adds at least +10 to the sexiness factor.