Each human body has its own particular smell, and we are quite familiar with our own individual smells. Distinctive smells of sweat or faeces (poo) are well known to all of us. As the body goes through its sexual development, it also produces chemicals that have particular effects on the smell of the body.
These chemicals are contained in the natural substances the body releases, like sweat, Vaginal fluid or Semen. Thus most smells are not associated with any Infections.
If someone’s personal hygiene is not taken care of, then these substances build up, and the smells get stronger. Washing daily, and giving particular care to areas where substances could build up (for example under the foreskin of an uncircumcised man or boy, or the Vaginal area of a woman or girl) will mean any mild smells are meant to be there and should not become unpleasant.
Some infections also cause the release of other substances from the body. These substances can have distinctive and sometimes unpleasant smells that go with them. It might be that an unusual Discharge carries a particular smell, or is an unusual colour, and this could be a clue to the presence of an infection. (An example of this is bacterial vaginosis.) This website contains details of several sexually-transmitted infections and non sexually-transmitted Genital infections.
If you notice anything that you would consider to be out of the ordinary for your body, then you can talk to your family doctor about it or make an appointment at your local genitourinary medicine clinic. See the directory of services.