This song seems to just convey the message that evil is sexy. The twin would "stink of sex appeal" and "all men would writhe beneath his scythe" and then "bring the pretty ones to me/and they would that I was he." Given Stephin Merritt's sexual orientation, this would be more than agreeable. And also, it would seem that it doesn't make much since that the twin would stink of sex appeal when Stephin doesn't, but then you realize that the sex appeal comes from the fact that the twin is evil.
This song seems to just convey the message that evil is sexy. The twin would "stink of sex appeal" and "all men would writhe beneath his scythe" and then "bring the pretty ones to me/and they would that I was he." Given Stephin Merritt's sexual orientation, this would be more than agreeable. And also, it would seem that it doesn't make much since that the twin would stink of sex appeal when Stephin doesn't, but then you realize that the sex appeal comes from the fact that the twin is evil.
Conclusion: the song is about how evil is sexy.