If you ever find yourself in a "need to pack wet clothes in checked bag" situation, just make sure that they are completely sealed and segregated from everything else (also try to displace as much air from their container as possible...limiting the supply of oxygen that is required for mold/bacteria to grow). It's unlikely that any mold will build up over the course of the rare "several days" scenario, but if it did, it would be limited to the wet clothes only...and, washing them (after you receive them) in as warm a water as the fabrics can tolerate with a good detergent (twice, if necessary) should completely eliminate any mold and/or bad smells.