Re: bathroom ceiling painting
Does it always peel down to the same layer? If so, then it could be an oil paint layer that wasn't primed before latex was applied. The transition from oil to latex requires a primer for the latex to adhere well.
As for the cracking, it is likely an excessive moisture issue, most likely from the shower and not venting well enough after each use. Your bathroom probably has poor air flow characteristics which makes everything worse.
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