I have tried oil-pulling in past. It feels quite refreshing and it sort of becomes a habit to feel that fresh again every morning. I only gave it up since it was taking up too much of my time. My family vouches for it to be healthy habit. I have seen it improve my allergic sneezing especially in the mornings, and my dust allergy.
I dont believe that it works by removing toxins by capillary action or any other bullshit. But have you ever tried to emulisify oil by swirling it around your mouth for 15 minutes? It is a big pain to do it. Oil is very viscous and thinning it by mixing it with saliva requires great effort. Doing so will give you a nice and steady 10-15 minute work out for your throat muscles and improves your breathing. Ultimately, the health benefits may stem from this rather than removal of any "toxins".