Generally, the laws regarding habitability do not concern cosmetic issues, such as ugly paint. However, you should check if the paint is lead based, which you may then have to have removed. But wouldn't it be nice if your new tenants came to a freshly painted residence. They may treat the residence with more respect.
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There is no legal requirement to paint a rental unit before reletting it to a new tenent. So long as the residence is habitable and not inviolation of code, you may determine how it looks or if it is painted.