I own shag carpet, which was popular a few years ago, that has unfortunately not lived up to it's promise. I was told it wouldn't show footprints through your carpet where you walk in high traffic areas. Although this is true, it's much worse. It now looks like a running track through certain parts of the high traffic areas.
The hallway and living room are the worst. I use a carpet rake, which by the way does not work well. After using this Hoover Platinum Lightweight Upright Vacuum, my friese carpet looks brand new.