After a year with Miele, I got a doggie smell every time I vacuumed. I was changing bags and smaller filters all the time, but it didn't matter. Then I found that while the sticker on this type of filter in my vacuum didn't indicate it needed to be replaced, it was likely the source of the odor. It was. As soon as I changed it, the dog smell (we have several large breed dogs) disappeared. Easy to change and makes the air smell much better!