Honestly, depending on the specifics here, not the worst. If they're using an oil that will polymerize, then as they oil/heat/cool cycle it, the seasoning will further develop over time, as long as they're somewhat scraping off remnants of their cooking as they finish, leaving it as clean as it can be without actually washing it, and then heat cycling it to sanitize any bacteria that might be there, I don't really see a problem with it....
It's not exactly up to modern hygienic standards, or social standards.... And I'm pretty sure if any restaurant or food joint did the same they would get shut down by the health inspector before long.... But you do you buddy.
For anyone not in the know, the thing with cast iron and cleaning is no longer a problem. Clean your cast iron. When cast iron was just about the only cookware, soaps included lye. Lye will erode the non-stick "seasoning" on cast iron. Modern soaps do not contain lye, so go ham.
Cleaning, however, introduces water.... And water causes iron to rust, so it is generally advisable to clean your cast iron cookware, then immediately heat it up past the boiling point for water, to vaporize any liquid water and carry it off the surface of the iron. Once past that temperature, let the cookware cool, then treat it with a thin layer of oil. This will protect the surface from atmospheric moisture and allow the cookware to work over much longer periods of time without needing to be "re-seasoned" (which is removing the layers of polymerized oil on the cast iron, and then re-applying it using a slow method of oiling, then heating the cookware, allowing it to cool, oiling then heating again)...
Don't be afraid of cast iron, it needs a little more attention than other cookware, but it's a joy to actually cook with.