Answer
A possessor in good faith — one who is unaware of any flaw in his title or mode of acquisition — is entitled to the fruits received before his possession is legally interrupted (Civil Code Article 544). A possessor in bad faith, by contrast, must reimburse the fruits received and those the lawful possessor could have received (Article 549).
As to expenses, necessary expenses are refunded to every possessor, but only the possessor in good faith may retain the thing until he is reimbursed (Article 546). Useful expenses are refunded only to the possessor in good faith, and the owner has the option either to pay the amount spent or to pay the increase in value the thing acquired; the good-faith possessor also enjoys a right of retention until he is paid (Articles 546 and 547).