Okay, the "Men Leave the toilet lid up" arguement with the inevitable male response of "why should I put it down, why doesn't she put it up" really misses the whole point people.
This isn't a convenience thing, it's a hygiene thing. If I walk into my bathroom and the lid is up --it means someone flushed the toilet with the lid up --which means that all the things that were in the toilet swirled around the air in the room where MY TOOTHBRUSH RESIDES... Now, I don't know about you, but for me the ONE SECOND act of putting both lids down is well worth not having urine and fecal matter on a brush that goes in my mouth (or towels, washcloths, etc.)
"Rinse your toothbrush thoroughly and let it dry out (don't put a cover on it or soak it). (Another way to avoid germ growth on your toothbrush is to make sure your toilet lid is down when you flush. Believe it or not, flushing with the toilet lid up contributes to spreading bacteria, and in the bathroom it can end up on your toothbrush.)" (source)
This isn't a gender issue. It's a don't-be-gross issue.
There. Solved. Now you have one less marital debate to worry about.