folks do funny things in houses. i worked on a house where they just vented everything into the attic including the dryer
I bought a house like that this summer. Builder put cheap weak fans in the bathroom and just stapled a flexible dryer hose up close to the ridge vent. Only had a little mold on the sheathing but had water dripping out of the fan from condensation in the vent line as soon as it got cold this autumn. I replaced them with better models, new 4" PVC venting out the side of the house, made sure to pitch it to the outside so any condensation that did accumulate ran out of the vent not back into the bathroom, and also covered them with insulation. I think I'm in good shape now.
The one I put in our master bathroom has a nice feature that I haven't seen before, it has a light as well as a nightlight that I wired to constant-on power. A 4w nightlight bulb gives off just enough light so I can take a whiz at night without burning up my eyes with the main light.
