I live in an apartment and as much as I'm a college student, I'm pretty ocd when it comes to cleaning. I vacuum once a week, dust, wipe, and just overall clean everything there is to clean. However, give it 3 days, and there will be dust on my TV stand, my desk (I have a black glass desk... bright idea), and my bookcases.

My friend told me to get an air purifier, but I've always been unsure of those... do they really do that good of a job?

You must live in a dusty part of the country. Dust can sneek in even with closed windows. I found that air purifiers are OK but they just seem to stir up the dust more than eliminate it. You could try one and see how you like it. Some of the newer ones are OK.

I did find that my dust problem abated a lot when I got a Kirby vacuum. It was an older model and I saved a bunch of $ on it. Yes, they are heavy, etc. but what happens essentially when you vacuum you are pulling all the dust out of your carpet and throwing it up into the air with very little going into the actual filter bags. Long story. You could also get good results when you vacuum if you use a HEPPA filter bag in the vacuum cleaner. That helps a lot. Also, you need to clean your carpets of the excess dirt. The real dirt hides at the base of the carpet and needs to be removed or it just keeps building up and up. Don't use any of those shake on air fresheners on your carpet either as they just build up inside your carpet and just literally cake up the base of the carpet. If you have throw rugs, wash them regularly also. Look downward if you want to solve your dirt mystery as it's most likely where you walk that's the culprit.