Technical question on "mild cam"

TT5.9mag said

Pull a valve cover off and look for adjustable valvetrain. If someone stuck a solid cam in it, and it needs lash adjustment then adjustable rockers will be there. If it has non adjustable factory type rockers then the chances that it has a hydraulic cam in it is about 99.9% and won’t need adjustment. But I have a question for you, you said “the engine runs great, currently…”. If that’s true why are you tearing it down?

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Well, there are other things the previous owner said that I have since found out were either incorrect or deliberate falsehoods. :) There's a bit of a fumey (fume bases?) cloud when it's running, and it is most likely just running rich, but I plan to at least get into it a bit to judge for myself if there's sludge, if the rings/pistons/cylinders seem alright. Plus, I'd hate to get it all together just to have something go wrong that I could have prevented, ya know?