The answer to 'why is my vacuum grimy' is that a grimy or dirty vacuum is usually caused by a buildup of dust, dirt, and debris inside the vacuum cleaner. This can happen over time as the vacuum is used to clean carpets, floors, and other surfaces. The dirt and debris can accumulate in the filters, the vacuum bag or canister, and other internal components, causing the vacuum to look and perform poorly.
Some common symptoms of a grimy vacuum include reduced suction power, visible dirt and dust in the vacuum bag or canister, and a musty or unpleasant odor coming from the vacuum. To fix a grimy vacuum, you'll need to clean or replace the filters, empty the vacuum bag or canister, and thoroughly clean the interior of the vacuum using the manufacturer's recommended maintenance procedures.