I don't know the exact science/medical (or whatever) reasons behind it, but I have noticed the same thing. Some of my favorite fragrances no longer appeal to me whereas some frags that I absolutely hated before have become my new favorites. I think some of it has to do with my smell senses maturing, but I have also noticed that different frags literally smell very different on my skin from day to day. I don't know if it has to do with different foods/spices that I have eaten that day/week or if there is some other reason, but some of my frags smell great on me one day then two weeks later they reek. I'm sure Luca Turin has something on his website or in a book somewhere that explains it.