i was in a grocery store that i’m not familiar with so i walked by produce and immediately i thought “paint thinner? why is there paint thinner in a grocery store and what are they using it for during business hours?”
it was the apples! 
my smeller is super sensitive to begin with but paint thinner? lol
This happened to me last weekend. Well, not the paint thinner smell, but I definitely was like “eeewwww it smells like rotten fruit over here”.
Kind of reminds me of that episode of King of the Hill where Bobby can smell that the milk in the fridge is about to go bad because he is taking ADD meds. LOL
Wax is applied to coat the apples. I wonder if it is that you were smelling. No doubt though that being in ketosis you pick up on smells more acutely.
I don’t know if it is purely smells but taste as well I’ve noticed I’ve been able to taste small flavors and subtleties as well.
For my Great Great Aunt’s 90th B-day we took her out to eat; everyone ate and had a great time. When dinner was done, people were wanting dessert and my mother ordered an Italian crème cake.
long story short, my mother didn’t want to feel like a glutton for getting it and was offering to everyone. Being the “good and noble son” I am ( I doubt she would agree 
) , I told her I would try a bite (I wouldn’t die after having one bite and plus sweet’s are irrelevant to me now at my stage in keto)
I tell ya guys, after having that bite not only was it a sweetness overload (duh) for me but I could taste… lime in it??? my wife is doing keto with me too and was able to pick up on a lime taste as well, but interestingly enough my mom wasn’t.
Is that normal for anyone else, being able to pick small subtle tastes out of things too???