I've only bought the pan a week ago and used it three times. Hot dogs, eggs, and steak.
When I'm done I clean it with a scrubby sponge and once with a little bit of detergent, then put it on the stove to dry quickly. Then while it's hot I smear maybe a teaspoon of vegetable oil on it with a paper towel "brush".
In between uses it's wet with oil, as you can see in the picture. How much residual oil should there be? I had the impression that it would be dryer.
Also, how much should I scrub? I am not going to leave crust of beef on there, but I also don't think it's supposed to be scrubbed back to new smoothness.
You want to make sure you aren't using a lye-based soap. Dr. bronners falls in this category and can take a bit of your seasoning off, at least if they haven't changed their soaps in 10 years. It shouldn't ruin your seasoning, but it can remove some of it and leave it a matte finish. Dawn and normal grocery store dish soaps won't hurt anything.