Everyone is idiosyncratic and has their own definitions of cleanliness.
When it comes to me touching other people (make-up/hair) or their food, I'm very conscientious as I feel responsible. I wash my hands and change gloves upon touching 'contaminants', I use disposable applicators and actually dispose of them after 1 use, I don't double dip, I do use hand sanitizer if soap and water are not readily available.
My idiosyncrasy is that I'm very aware of all the germs crawling over public surfaces like door handles, telephone receivers, faucets. I try to use a napkin to turn the faucet off and open the restroom door upon exiting (or else use my pinky).
I greatly prefer not to share utensils or drinks with people -- I'm all about cooties this way. I would also NEVER grab ANYTHING or even sort through the garbage can, I don't care if the garbage can is 'new' or if it was only there for 5 seconds.
BUT -- otherwise, yeah I probably do (or don't) do things that make others cringe.
EX 1: I like dogs so I don't mind doggie slobber (I'm not gonna french my dog though ) I once had to reach into a dog's mouth at a picnic (didn't know the dog) to get chicken bones out of its mouth lest it choke. My friend laughed at me because she thought it was gross -- and she's the one who gave the bones to the dog!
EX 2: I LOVE street food and is one thing I look forward to when travelling abroad. I'll eat food that's been sitting out. I eat at a lot of hole in the wall restaurants -- those generally have questionable sanitation. I used to live in a country where Hepatitis C is common (through saliva i.e. sharing food, utensils) and now autoclaves are common sights at fast food joints.
Overall I have a pretty strong stomach, and I agree, if it doesn't kill you it'll make you stronger. The acids in your stomach kill most cooties, yes? I rarely get sick, maybe 1x a year. Your body needs a chance to build up antibodies. And as long as no one is PURPOSELY doing something disgusting to my food, I'm pretty okay being oblivious.