I just take my registers and return air grills ( where most of the crap settles) off and take a good shop vac and stick the hose in there and vacume them out real good.
Dryer vent , depending if it's the floppy flex stuff or hard pipe. If it hard pipe you can get a long 4 inch brush and run it in and out of the pipe also. If it's flex, and easily accessible I just replace it.