Still single in the mid 30's... is there something wrong with you?

So, I'm ... ahem... in my mid 30's these days.  (Where did the time go?? I started this blog when I wasn't quite 30 and I still 35 this year!).  One of the things my friends and I have been chatting about lately is the idea that there is something wrong with you if you are still single in your mid 30's. 

Now, don't get me wrong... many of us who are single in our mid 30's (and above) are damn good catches, but the idea that we are still single (male or female) does beg the question - Why are you still single?

Now don't get me wrong, there are hundreds (probably thousands) of reasons why someone could still be single.  You know, they were married at one point (and now divorced), they traveled a lot, they were continuing their education, etc.  But there are a handful of us who really don't have a reason.  We are just still single. 

I like to blame the fact that I was fat (I've since lost 110 lbs) and that I was a dedicated career women (I regularly work a whole lot of OT, but also have since decided to work less).  So, I have excuses, but they are just that...excuses.  To date, I just haven't met my intended... and I will argue reasons all day with you - I'm very very good with justifications.

But say I meet some new guy and he doesn't have a GOOD reason that he's still single, I can't help but wonder why.  What is his fatal flaw (or god forbid... FLAWS) that have kept him single.  Was he a player?  A jerk? or others?

So... what do you think (men and women), is there something inherently wrong with someone who is still single in their mid 30's (without a good reason?)