You are obligated to provide a livable housing. That is plumbing, electricity, water, heating, gas, window, doors...
Paint has nothing to do with livability (legal word: habitability). If they didn't like the paint, they don't have to sign the lease.
You don't even have to allow them to repaint the walls. 你需要提高业务水平,出租房不是只收房租啊。
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