i think people replace brush heads to readily a lot of the time, i don't worry about a bit of a ragged brush with birds muck i scrub it and then come back to it so your never really working very hard, a soaked birds mess will come off with anything. i have had gardiners brushes with bristlls all over and still they are quick light and good, if you do fancy a new brush though i have been very impressed with the sill brushes