The X-factor theory suggest's there are other factors to attraction other than Looks or Personality but we cannot point at it, because we can't see it. This theory was developed because of observations outside of dating apps and internet dating culture. HBTDL noticed that alot of dads nowdays are bald,fat or either unkempt. this concept was later referred to as the "schluby hubby" theory.
HBTDL said "if woman seek the best genes for their offspring, then why they are happily raising defective children? (retards,autisms etc). this can also be seen with the rise of the soyboy. and how its not necessarily looks that affect the overall dating situation for men. also, in his words. if woman are looking for a domineering man that takes charge, then why they accept things like stay at home dads soyboys? Beyond Hypergamy, woman typically go for stereotypes - anything odd or less than NT would be considered an impediment. it does not matter if you are the worst person around, what matters is that you portray a stereotype that woman accept in a universal way. (for example: soyboy's,thugs,juiceheads etc). but still, this theory alone would not solve factor X. as we still don't know what attracts "woman". and perhaps we should also look at facts beyond statistics in order to find the missing link.