Sexual markets are vulnerable to changes in the incentives for paternal investment. (Paternal investment itself is a crucial aspect of the sexual market.) As women become more economically self-sufficient and sexually liberated their mate acquisition algorithm begins to emphasize the targeting of men for sexual and romantic validation and to undervalue men who would make dependable resource providers.Essentially, they're trying to elevate their short-term SMV at the expense of their longer term MMV, presumably because they see no real prospects of getting married or being supported by a husband anyhow.
Likewise, men who are less interested in commitment and family formation would seek out women primarily for sexual thrills rather than their maternal instinct or faithfulness.
If this is the operative sexual market, then tattoos and single mommery would not only have little effect on women’s SMVs, they may very well raise their SMVs by advertising a greater willingness to go all the way right away, (and to not make much of a fuss when she’s dumped post-chaste).
Now ask yourself, where do you see women with lots of garish tattoos and bastard spawn? The lower classes. And where do you see less dependable fly-by-night men? The lower classes. In the upper classes single mommery is still rare and tattoos, though more common than they once were, are tastefully inconspicuous. Obesity, too, is rarer among upper class women.
So it’s in the lower classes (now gradually expanding into the working and middle classes) where the sexual market has responded to the changing incentives and women have resorted to more “slut signaling” accoutrements like tattoos, skimpy trashy clothes, and yes even bastard spawn (a single mom is a slutty mom).
In the upper classes, paternal investment is still important, so we see less of this among the women who have kept to the traditional SMV norms of their sex: slenderness, clear skin, and childlessness.
They appeal to men in the short-term for the same reason players appeal to nice girls; they are unlikely to kick up a fuss or cause any problems when the other party moves on. After all, if a woman is covered with tattoos and oozing with attitude, you can be pretty sure that she's not looking for a husband or even a serious relationship.