The Worst Job in the World?

I couldn't be a dentist. Mouths are the ickiest orifice.

As a dentist I can think of ickier bits of the body. 
Im lucky in as much as most people who come to the dentist are fit and clean their teeth so the majority of my patients are easy to examine and have nothing wrong. As a GP or specialist doctor (gynaecology, proctology etc) the only time you examine someone is when they have a problem and as such is much more likely to smell, be unpleasant etc. 

I used to live with a podiatry student and neither of us could understand the other ones interest in their field. 

As for jobs I couldn't do I'm not in to heights so painting the forth Bridge or cleaning sky scraper windows isn't my idea of fun.