An uncircumcised penis will normally have a very faint aroma, but one that you can only smell if you are very close to it. This is not an unpleasent smell, and is just the slightly damp mucosa lubricating the glans as nature intended.
If you do not wash your penis after ejacualation it will get very smelly after a while, and will take a day or so of washing to get back to the normal very faint aroma. Also if you do not wash under the foreskin regularly there can be a build up of smegma which is a white dry substance that forms, again quite naturally under the foreskin. In itself smegma is not bad, but a build up could be the cause of the smell you report.
In order to wash your penis properly make sure you can retract your forskin all the way back, and then use a gentle soap and wash it thoroughly in the shower at at least daily. Then make sure you rinse it very well
. Use soap or shower gel to wash around your groin and under your scrotum as well as this can also build up bacteria which will start to smell.
If you are masturbating a lot, wash your penis after every ejaculation in the same way, but you may just want to run some water in a basin and use a cloth instead of having many showers in a day!
If you are circumcised, I would think that there should be no smell as the mucosa will be hard and dry, and it would get washed routinely in the shower just by standing there!
brian1458 
does it hav 2 do with size?
