A lot of good comments here.

A different way to approach this problem, is to consider culture: 'people like us, are attracted to certain things'.

Those fields are overwhelmed.

So, where are the 'completely unsexy' areas?

1) Human Waste. Port-o-potties are a huge business, and it's a nasty problem, pun intended.

2) Agriculture. Farms are not hip.

3) A lot of goods and services targeting low-income people who are extremely price sensitive and don't care about how cool things look.

4) Anything to do with a business that is mundane: cleaning, forensic accounting, physical security, garbage, etc..

Literally walk down the street and look at what people do, it's funny how you can get an instinct for how very 'specific' YC pattern types are, and how we're a little bit out of touch.