I'm not sure if I notice bitterness in a scent normally, but I do know coffee does it for me. Ohh how I despise bitter flavours - they're too strong! I've had someone brew me a good large mug of chocolate milk and put a teaspoon of his own brewed coffee into it. The chocolate milk turned so bitter and disgusting, even though he tried to cover it by adding more sugar.
Many scents actually can make me feel sick. So whilst I love my lemon balm in my garden, if I take it up to my face and sniff it's too strong and I start feeling dizzy and get headaches. I'm the only one in my family that gets like that, and growing up they often thought I was overreacting.
I wonder if there's a way to test it without the DNA test, as I hear that people have had loads of issues with their information leaking or something like that. Someone I knew actually got recognised as a "terrorist" (he isn't) by the state after a DNA test and isn't allowed on planes. Not a clue how that worked out as everyone around him (friends and family alike) were just as confused.
Maybe he just dramatized the story for all I know, but I do know he isn't allowed on ANY planes for whatever reason then.
I am very sensitive to a lot of flavours and scents. Whilst I love eating sweet food, a warm sweet scent is too strong and makes me feel really queasy. I love eating 'Sweet and Sour pineapple chicken' but if I accidentally smell it whilst cooking it's too much and I can't stand eating it anymore. If I don't smell it, yeah it's really, really sweet but also really quite nice.
I would say about the only thing that doesn't set me off is salt. Perhaps because it doesn't really have a scent. But the smell of the sea does get a bit much for me at times, even though I love the beach and the waves. Maybe because of all the other scents mixed in... who knows.
It's very interesting to actually think about it, because to me this has always been my "normal". It's fun to sometimes step back and be like "hey, not everyone experiences it like that".