Once at a previous job I commented to the lady who sat near me that I could smell cigar smoke. You know that horrible smell like burning socks. She couldn't smell it but I assumed it was coming from the door near by. I kept noticing it all day long, a whiff of awful stench would drift in to my cube. I kept trying to figure out where it was coming from. After all I didn't think there was someone standing outside the door smoking all day long. Eventually my co worker came in to my cube to see if she could smell it and I realised it was her perfume. GAG!
Sadly someone I work with now seems fond of the same brand.