It’s not about the smell, its venting moist air into the attic which causes it to get trapped and promote mold growth like with a sweaty gym sock. The people who built my house just used string to point the vent pipes toward the standard screened roof vents and even that has been an issue. They should ideally be exhausted through the roof with purpose built vents. Even exhausting through the wall or soffit can be an issue as air gets sucked in through the soffit which can pull that hot air with it.