I clean the lint filters on my Maytag washer and Frigidaire dryer after every use. I have five cats and two dogs so about every three months I clean the dryer with the shop vac, and check the dryer vent for buildup.
I can't believe people are that lazy or stupid not to clean the lint filters. It's just as bad as people who don't ever empty their vacuum cleaner bags. A friend of mine just go a free Kirby Heritage II of of FreeCycle, owner claims it didn't work. He brought to me to look at the bag was overfilled and the tube was packed with dirt. Took all apart, cleaned it with the shop vac, washed the cloth bag, and now it works perfectly. Some people are just plain idiots I guess.