You can make things smell a little off

You can make anything in a 50 meter radius of you smell just weird enough to throw someone off but not enough to be alarming

it doesn't change the chemical composition of anything, it changes how people in a 50 meter radius of you detect the smell of certain things

Its not a curse, you can make individual things smell off, it instantly stops when you are away from the thing

A good use would be making gas smell weird so you can detect a gas leak

A bad use would be making air and other things smell weird in someone's house and making them paranoid

A drawback would be them suspecting that the smell is coming from you because of it disappearing when you are away