I have had some oil bath filters where the air just flowed past a puddle of oil. Probably not effective.
But I also had a huge one on a Toyota LandCrusher that was deigned to draw air down into & then up through a huge oil reservoir. If you cleaned the housing, filled it with the proper amount of oil, (2 qts?) and then ran at high RPM, there was oil residue about 4-5" higher than the oil static level inside the housing. I imagine it filtered pretty well, judging by the amount of sediment (and pea gravel
) I had to clean out periodically.
I was told it was an option for the african continent, along with the snorkel that drew air from the glove box.