The latest Caracol reviewer mentioned bad sewer odors in both bathrooms. I always take some plastic and tape to cover the bathroom fresh air opening if the mosquitoes are bad. I've never had to use it for mosquitoes, but in Dec. there was sewer gas odor, so I taped the plastic over the floor drain under the sink. That fixed the problem and the maids left it alone. An even easier fix would be to dump a glass of water into the drain. The standing water in the drain trap had probably gone stagnant or evaporated and fresh water would properly seal the trap again.