Sorry, but this IS NOT TRUE.
I spent $295 on a 12" fan and another $325 on 1.25 CanFilter- and my next door neighbor bitched at me just a couple weeks ago because my house reeks. Yes, I'm damn sure I installed it correctly. No, there were no leaks or gaps because the fan was mounted directly to the filter it was pulling through and the seams were taped. The simple fact is that you do not want to blindly trust a carbon filter. Use your nose, and be sure to direct smell away from confined spaces- straight up is best.
I'm very disappointed that my expenditure did not achieve the promised results, and therefore I think it's important that others know of my experience so they aren't caught by surprise like I was.
Fortunately, my neighbor is a reasonable guy, and when he learned that I had gone to such extremes to protect his air quality, he was willing to cut me some slack to rearrange things.