Clean filters, be they paper or oiled allow air to pass through in a fairly free manner.The air is not going to pull the clean oil through a clean element up and over the top, rather it drips down into the bottom of the box far away from the snorkel and throttle body, even more so as the oil gets warm.
The gunk, oil/dirt/crud found in the throttle body passages is more likely from the condensed vapor coming from the breather tubes. It gets there in the throttle body when the air filter element is clogged and not allowing air to flow as it should through the filter into the motor. Regardless, if the filter is the stock paper one or an oiled one, once the filter is clogged and the air flow cut down, more gets pulled from the breathers. Pull excessive vapor from the breathers and you're going to clog up the throttle body much faster. Because the clog is oil/dirt people remember the oiled filter and blame that. I believe they are mistaken.
Cars with paper filters will get gunk-ed up throttle passages too but because the service interval is so high (30k miles) it is not as common as the element does not get clogged by the small parts of dry dirt causing increasing pull on other air sources.
Oiled filters have a much shorter service interval. The dirt hits the oiled element and unlike the paper filter, in the oiled one the dirt swells as it absorbs the oil. The dirt acts like a sponge and when it gets soaked it swells taking up a larger area and impeding airflow.
Race teams that use these filters clean them after every race.
Most folks stick them in and let them stay too long expecting a stock-like service interval.
Everyone of the oiled filters I've seen at my shop has been clogged with a big dark spot when I checked them.
I clean mine(I have a CTSC) every 1k miles because with the SC it demands more air.
I have two and swap them out cleaning/oiling the one I take out and storing it in a zip-lok bag until the next change. I feel this is the best method. You will need less filter oil as well because being stored it has more time to thoroughly permeate the foam element.
If a person is not willing to do the increased the maintenance with these oiled filters I suggest they go back to the stock paper ones. This will help them to avoid the odd idle and stalling a dirty TB can cause.
