Well, if you ovariectomize rats then treat them with estradiol to simulate their estrus cycle and induce mating behavior, then put males in with them and score the behavior, males definitely respond to different females differently. Sometimes they’ll very aggressively pursue a female, and sometimes they don’t seem to care that she’s even there. It seems to depend on a lot of factors- the age of the male, the age of the female, how many females he’s mated with, etc., but there does also seem to be some variation in female attractiveness.
Some females, all the males we put in with them chase them around the whole time they’re together, whereas others aren’t nearly as motivating. Other females were irresistible to some males but “meh” to others, so there seemed to be a bit of variability. It may be a scent thing, but a lot of it is behavior. Some rats in estrus exhibit obvious ear wiggling and bunny hopping behaviors that make them more attractive, so obviously the females that “acted sexy” got more action.
That’s my sum total of experience with relative animal attractiveness, and, not being rats, we didn’t even attempt to quantify the attractiveness of each female. We just noticed that the desirable females were better for our experiments because we were studying female behavior, and the more “attractive” the female was, the easier it was for us to get good scores for her.
I’m not sure that answers your question, but to sum up: in my experience, some rats are more attractive to males then others, so an extra-attractive rat seems plausible to me.