Each community will have its own Covenants and Restrictions (CC&Rs). Laws and regulations governing these CC&Rs can also be different in each state. Request a copy of the conditions and terms defining "adult" and also make sure those rules are fully legal. I have seen communities where its OK to "visit" for a lengthy period, where an "adult" can have a grandchild living with them based on the rules of the commuity and/or hardship cases, where an "adult" must own and then someone else can rent, and all kinds of other mis-matched, non-standardized rules exist. Consult the rulebook, the laws, then an attorney if things aren't making sense to you. Best!