The manufacturers of bagless vacuums advertise their filters as washable. But are they really? Foam and sponge ones are. However you need to be sure they are thoroughly washed and completely dry. A sunny window does best for drying. In our experience they do not stay effective as a filter after so many washes and need to be replaced. The reason why is that powder type dirt stays in the filter and build up and do not let optimum air pass through. They also break down and compress with washings.
The pleated HEPA type filters should never be washed and need replacing regularly. At least once a year. Not doing these small maintenance duties will affect any machines performance.