the top may have animal hair on it but that doesn't mean its dirty, or even had an animal on it. Their hair flies thru the air and gets onto everything. My animals don't come into my sewing room but I still find hair there. It gets caught up in the filter and the vent. I have a front loader and I'd worry more about the pump getting clogged than the dryer. I do agree that I would never put muddy wet clothes in there, but that's different.