I meant to post this some time ago. A new study showed that older, cheaper vacuums can actually generate more dust and bacteria than they vacuum up. Some of the newer HEPA vacuums were net positive, as they stirred up some dust but vacuumed up more.
This line of thought occurred to me when we were vacuuming last year. It seemed like every time we vacuumed, everyone had some nasal congestion the next day.
This led me to break down and buy a Dyson vacuum cleaner. I didn't want to pay that much for a vacuum cleaner, but this new study does confirm that it actually reduces household dust instead of increasing it.