I find that most the folks, both men and women, who lament their inability to find someone worth dating generally fall into 2 camps.
1) They are people who DO NOTHING... literally.. they go to work, and they go home, and if they do anything its with their family... This is not conducive to meeting new people, which is what is neccessary to find folks worth dating.
or
2) They have unrealistic expectations.. If you are 100lbs overweight, the likehood of you being able to get a date with the gal with the perfect figure, or the guy with the 6 pack abs is greatly reduced. A 8 has a chance with a 10... a 7 with a great personality might be able to get there... but a 5 is not going to bag a 10... most of the time. If you have absolutely ZERO personality, even if you are good looking you are going to have a hard time having any kind of long term relationship...
Basically it boils down the old axiom... Sex discriminates against the shy and the ugly.